INTERNET-DRAFT                 Geoffrey Clemm,
Network Working Group                                           G. Clemm
Internet-Draft                                                       IBM
    draft-ietf-webdav-acl-12       Anne Hopkins, Microsoft Corporation
				   Eric Sedlar,
Expires: June 22, 2004                                        J. Reschke
                                                              greenbytes
                                                               E. Sedlar
                                                      Oracle Corporation
				   Jim Whitehead,
                                                            J. Whitehead
                                                         U.C. Santa Cruz

    Expires April 10, 2004         October 10,
                                                       December 23, 2003

                     WebDAV Access Control Protocol
                        draft-ietf-webdav-acl-13

Status of this Memo

   This document is an Internet-Draft and is subject to in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
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    http://www.ietf.org/ietf/1id-abstracts.txt http://
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   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on June 22, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

   This document specifies a set of methods, headers, message bodies,
   properties, and reports that define Access Control extensions to the
   WebDAV Distributed Authoring Protocol. This protocol permits a client
   to read and modify access control lists that instruct a server
   whether to allow or deny operations upon a resource (such as
   HyperText Transfer Protocol (HTTP) method invocations) by a given
   principal. A lightweight representation of principals as Web
   resources supports integration of a wide range of user management
   repositories. Search operations allow discovery and manipulation of
   principals using human names.

   This document is a product of the Web Distributed Authoring and
   Versioning (WebDAV) working group of the Internet Engineering Task
   Force. Comments on this draft are welcomed, and should be addressed
   to the acl@webdav.org [1] mailing list. Other related documents can
   be found at http://www.example.com/acl/, [2], and
    http://www.ics.uci.edu/pub/ietf/webdav/.

    Clemm, Hopkins, Sedlar, Whitehead
			      [Page 1] [3].

Table of Contents

    1 INTRODUCTION.................................................4

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  5
   1.1 Terms......................................................6   Terms  . . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   1.2   Notational Conventions.....................................7

    2 PRINCIPALS...................................................7

    3 PRIVILEGES...................................................8 Conventions . . . . . . . . . . . . . . . . . . .  8
   2.    Principals . . . . . . . . . . . . . . . . . . . . . . . . .  8
   3.    Privileges . . . . . . . . . . . . . . . . . . . . . . . . .  9
   3.1   DAV:read Privilege.........................................9 Privilege . . . . . . . . . . . . . . . . . . . . . 10
   3.2   DAV:write Privilege........................................9 Privilege  . . . . . . . . . . . . . . . . . . . . 11
   3.3 DAV:write-properties.......................................9   DAV:write-properties Privilege . . . . . . . . . . . . . . . 11
   3.4 DAV:write-content.........................................10   DAV:write-content Privilege  . . . . . . . . . . . . . . . . 11
   3.5 DAV:unlock................................................10
    3.6 DAV:read-acl Privilege....................................10
    3.7 DAV:read-current-user-privilege-set Privilege.............10
    3.8 DAV:write-acl Privilege...................................11
    3.9   DAV:unlock Privilege . . . . . . . . . . . . . . . . . . . . 12
   3.6   DAV:read-acl Privilege . . . . . . . . . . . . . . . . . . . 12
   3.7   DAV:read-current-user-privilege-set Privilege  . . . . . . . 12
   3.8   DAV:write-acl Privilege  . . . . . . . . . . . . . . . . . . 13
   3.9   DAV:bind Privilege........................................11 Privilege . . . . . . . . . . . . . . . . . . . . . 13
   3.10  DAV:unbind Privilege.....................................11 Privilege . . . . . . . . . . . . . . . . . . . . 13
   3.11  DAV:all Privilege........................................11 Privilege  . . . . . . . . . . . . . . . . . . . . . 13
   3.12  Aggregation of Predefined Privileges.....................11

    4 PRINCIPAL PROPERTIES........................................12 Privileges . . . . . . . . . . . . 13
   4.    Principal Properties . . . . . . . . . . . . . . . . . . . . 14
   4.1 DAV:alternate-URI-set.....................................12   DAV:alternate-URI-set  . . . . . . . . . . . . . . . . . . . 14
   4.2 DAV:principal-URL.........................................12   DAV:principal-URL  . . . . . . . . . . . . . . . . . . . . . 15
   4.3 DAV:group-member-set......................................12   DAV:group-member-set . . . . . . . . . . . . . . . . . . . . 15
   4.4 DAV:group-membership......................................13

    5 ACCESS CONTROL PROPERTIES...................................13
    5.1 DAV:owner.................................................13
     5.1.1   DAV:group-membership . . . . . . . . . . . . . . . . . . . . 15
   5.    Access Control Properties  . . . . . . . . . . . . . . . . . 15
   5.1   DAV:owner  . . . . . . . . . . . . . . . . . . . . . . . . . 16
   5.1.1 Example: Retrieving DAV:owner..........................13 DAV:owner  . . . . . . . . . . . . . . . 16
   5.1.2 Example: An Attempt to Set DAV:owner...................14 DAV:owner . . . . . . . . . . . . 17
   5.2 DAV:supported-privilege-set...............................15
     5.2.1   DAV:group  . . . . . . . . . . . . . . . . . . . . . . . . . 18
   5.3   DAV:supported-privilege-set  . . . . . . . . . . . . . . . . 19
   5.3.1 Example: Retrieving a List of Privileges Supported on a Resource.............................................16
    5.3 DAV:current-user-privilege-set............................18
     5.3.1
         Resource . . . . . . . . . . . . . . . . . . . . . . . . . . 20
   5.4   DAV:current-user-privilege-set . . . . . . . . . . . . . . . 22
   5.4.1 Example: Retrieving the User's Current Set of Assigned
     Privileges...................................................19
    5.4 DAV:acl...................................................20
     5.4.1 ACE Principal..........................................20
     5.4.2 ACE Grant and Deny.....................................21
     5.4.3 ACE Protection.........................................21
     5.4.4 ACE Inheritance........................................21
     5.4.5 Example: Retrieving a Resource's Access Control List ..22
         Privileges . . . . . . . . . . . . . . . . . . . . . . . . . 23
   5.5 DAV: acl-restrictions.....................................23
     5.5.1 DAV:grant-only.........................................23
     5.5.2 DAV:no-invert ACE Constraint...........................24
     5.5.3 DAV:deny-before-grant..................................24
     5.5.4 Required Principals....................................24
     Example: Retrieving DAV:acl-restrictions.............     ...24
    5.6 DAV:inherited-acl-set.....................................25
    5.7 DAV:principal-collection-set..............................25
     5.7.1 Example: Retrieving DAV:principal-collection-set.......26
    5.8 Example: PROPFIND to retrieve access control properties...27

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 2] 
    6 ACL EVALUATION..............................................30

    7 ACCESS CONTROL AND EXISTING METHODS.........................31
    7.1 ANY HTTP METHOD...........................................32
     7.1.1 Error Handling.........................................32
    7.2 OPTIONS...................................................32
     7.2.1 Example - OPTIONS......................................33
    7.3 MOVE......................................................33
    7.4 COPY......................................................33
    7.5 LOCK......................................................33

    8 ACCESS CONTROL METHODS......................................33
    8.1 ACL.......................................................33
     8.1.1 ACL Preconditions......................................34
     8.1.2 Example: the ACL method................................35
     8.1.3 Example: ACL method failure due to protected   DAV:acl  . . . . . . . . . . . . . . . . . . . . . . . . . . 24
   5.5.1 ACE
           conflict...............................................36
     8.1.4 Example: ACL method failure due to an inherited Principal  . . . . . . . . . . . . . . . . . . . . . . . 24
   5.5.2 ACE
           conflict...............................................37
     8.1.5 Example: ACL method failure due to an attempt to set
           grant Grant and deny in a single ACE.........................38

    9 ACCESS CONTROL REPORTS......................................39
    9.1 REPORT Method.............................................39
    9.2 DAV:acl-principal-prop-set Report.........................39
     9.2.1 Example: DAV:acl-principal-prop-set Report.............40
    9.3 DAV:principal-match REPORT................................42
     9.3.1 Example: DAV:principal-match REPORT....................43
    9.4 DAV:principal-property-search REPORT......................43
     9.4.1 Matching...............................................45
     9.4.2 Example: successful DAV:principal-property-search
           REPORT.................................................46
    9.5 DAV:principal-search-property-set REPORT..................48
     9.5.1 Deny . . . . . . . . . . . . . . . . . . . . . 26
   5.5.3 ACE Protection . . . . . . . . . . . . . . . . . . . . . . . 26
   5.5.4 ACE Inheritance  . . . . . . . . . . . . . . . . . . . . . . 26
   5.5.5 Example: DAV:principal-search-property-set REPORT......49

    10  XML PROCESSING............................................50

    11  INTERNATIONALIZATION CONSIDERATIONS.......................50

    12  SECURITY CONSIDERATIONS...................................51
    12.1 Increased Risk of Compromised Users......................51
    12.2 Risks of the DAV:read-acl Retrieving a Resource's Access Control List . . . . 26
   5.6   DAV:acl-restrictions . . . . . . . . . . . . . . . . . . . . 28
   5.6.1 DAV:grant-only . . . . . . . . . . . . . . . . . . . . . . . 29
   5.6.2 DAV:no-invert ACE Constraint . . . . . . . . . . . . . . . . 29
   5.6.3 DAV:deny-before-grant  . . . . . . . . . . . . . . . . . . . 29
   5.6.4 Required Principals  . . . . . . . . . . . . . . . . . . . . 29
   5.6.5 Example: Retrieving DAV:acl-restrictions . . . . . . . . . . 30
   5.7   DAV:inherited-acl-set  . . . . . . . . . . . . . . . . . . . 31
   5.8   DAV:principal-collection-set . . . . . . . . . . . . . . . . 31
   5.8.1 Example: Retrieving DAV:principal-collection-set . . . . . . 32
   5.9   Example: PROPFIND to retrieve access control properties  . . 33
   6.    ACL Evaluation . . . . . . . . . . . . . . . . . . . . . . . 37
   7.    Access Control and existing methods  . . . . . . . . . . . . 39
   7.1   Any HTTP method  . . . . . . . . . . . . . . . . . . . . . . 39
   7.1.1 Error Handling . . . . . . . . . . . . . . . . . . . . . . . 39
   7.2   OPTIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . 40
   7.2.1 Example - OPTIONS  . . . . . . . . . . . . . . . . . . . . . 40
   7.3   MOVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
   7.4   COPY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
   7.5   LOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
   8.    Access Control Methods . . . . . . . . . . . . . . . . . . . 41
   8.1   ACL  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
   8.1.1 ACL Preconditions  . . . . . . . . . . . . . . . . . . . . . 42
   8.1.2 Example: the ACL method  . . . . . . . . . . . . . . . . . . 44
   8.1.3 Example: ACL method failure due to protected ACE conflict  . 45
   8.1.4 Example: ACL method failure due to an inherited ACE
         conflict . . . . . . . . . . . . . . . . . . . . . . . . . . 46
   8.1.5 Example: ACL method failure due to an attempt to set
         grant and deny in a single ACE . . . . . . . . . . . . . . . 47
   9.    Access Control Reports . . . . . . . . . . . . . . . . . . . 48
   9.1   REPORT Method  . . . . . . . . . . . . . . . . . . . . . . . 48
   9.2   DAV:acl-principal-prop-set Report  . . . . . . . . . . . . . 49
   9.2.1 Example: DAV:acl-principal-prop-set Report . . . . . . . . . 50
   9.3   DAV:principal-match REPORT . . . . . . . . . . . . . . . . . 51
   9.3.1 Example: DAV:principal-match REPORT  . . . . . . . . . . . . 52
   9.4   DAV:principal-property-search REPORT . . . . . . . . . . . . 53
   9.4.1 Matching . . . . . . . . . . . . . . . . . . . . . . . . . . 56
   9.4.2 Example: successful DAV:principal-property-search REPORT . . 56
   9.5   DAV:principal-search-property-set REPORT . . . . . . . . . . 58
   9.5.1 Example: DAV:principal-search-property-set REPORT  . . . . . 60
   10.   XML Processing . . . . . . . . . . . . . . . . . . . . . . . 61
   11.   Internationalization Considerations  . . . . . . . . . . . . 61
   12.   Security Considerations  . . . . . . . . . . . . . . . . . . 62
   12.1  Increased Risk of Compromised Users  . . . . . . . . . . . . 62
   12.2  Risks of the DAV:read-acl and
         DAV:current-user-privilege-set Privileges  . . . . . . . . . 63
   12.3  No Foreknowledge of Initial ACL  . . . . . . . . . . . . . . 63
   13.   Authentication . . . . . . . . . . . . . . . . . . . . . . . 64
   14.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . 64
   15.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 64
         Normative References . . . . . . . . . . . . . . . . . . . . 64
         Informative References . . . . . . . . . . . . . . . . . . . 65
         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 66
   A.    WebDAV XML Document Type Definition Addendum . . . . . . . . 67
   B.    WebDAV Method Privilege Table (Normative)  . . . . . . . . . 70
   C.    Resolved issues (to be removed by RFC Editor before
         publication) . . . . . . . . . . . . . . . . . . . . . . . . 71
   C.1   ED_references_names  . . . . . . . . . . . . . . . . . . . . 72
   C.2   ED_RFC2386 . . . . . . . . . . . . . . . . . . . . . . . . . 72
   C.3   ED_example_host_names  . . . . . . . . . . . . . . . . . . . 72
   C.4   ED_authors_list  . . . . . . . . . . . . . . . . . . . . . . 72
   C.5   ED_non_ASCII . . . . . . . . . . . . . . . . . . . . . . . . 73
   C.6   ED_artwork_line_width  . . . . . . . . . . . . . . . . . . . 73
   C.7   ED_xml_typos . . . . . . . . . . . . . . . . . . . . . . . . 73
   C.8   1_ref_options  . . . . . . . . . . . . . . . . . . . . . . . 73
   C.9   3.2_ED_RFC2518 . . . . . . . . . . . . . . . . . . . . . . . 74
   C.10  3.3_ED_priv_section_titles . . . . . . . . . . . . . . . . . 74
   C.11  3.4_write-content-description  . . . . . . . . . . . . . . . 74
   C.12  3.12_ED_bad_reference  . . . . . . . . . . . . . . . . . . . 75
   C.13  4.1_ED_RFC2589 . . . . . . . . . . . . . . . . . . . . . . . 75
   C.14  5.1_owner_group_details  . . . . . . . . . . . . . . . . . . 75
   C.15  5.1_owner_href_optional  . . . . . . . . . . . . . . . . . . 76
   C.16  5.1.2_responsedescription  . . . . . . . . . . . . . . . . . 76
   C.17  5.5.5_ED_section_numbering . . . . . . . . . . . . . . . . . 76
   C.18  5.8_unbind . . . . . . . . . . . . . . . . . . . . . . . . . 76
   C.19  6_ED_RFC3010 . . . . . . . . . . . . . . . . . . . . . . . . 77
   C.20  6_group_property . . . . . . . . . . . . . . . . . . . . . . 77
   C.21  5.5.2_TYPO . . . . . . . . . . . . . . . . . . . . . . . . . 77
   C.22  9.4_ED_reference_casemap . . . . . . . . . . . . . . . . . . 78
   C.23  11_ED_RFC2279  . . . . . . . . . . . . . . . . . . . . . . . 78
   C.24  A_ED_appendices  . . . . . . . . . . . . . . . . . . . . . . 78
         Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
         Intellectual Property and
         DAV:current-user-privilege-set Privileges................51
    12.3 No Foreknowledge of Initial ACL..........................52

    13  AUTHENTICATION............................................52

    14  IANA CONSIDERATIONS.......................................52

    15  INTELLECTUAL PROPERTY.....................................53

    16  ACKNOWLEDGEMENTS..........................................53

    17  REFERENCES................................................53
    17.1 Normative References.....................................53

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 3] 
    17.2 Informational References.................................54

    18  AUTHORS' ADDRESSES........................................55

    19  APPENDICES................................................56
    19.1 WebDAV XML Document Type Definition Addendum.............56
    19.2 WebDAV Method Privilege Table (Normative)................58

    1  INTRODUCTION Copyright Statements . . . . . . . 82

1. Introduction

   The goal of the WebDAV access control extensions is to provide an
   interoperable mechanism for handling discretionary access control for
   content and metadata managed by WebDAV servers.  WebDAV access
   control can be implemented on content repositories with security as
   simple as that of a UNIX file system, as well as more sophisticated
   models.  The underlying principle of access control is that who you
   are determines what operations you can perform on a resource. The
   "who you are" is defined by a "principal" identifier; users, client
   software, servers, and groups of the previous have principal
   identifiers. The "operations you can perform" are determined by a
   single "access control list" (ACL) associated with a resource.  An
   ACL contains a set of "access control entries" (ACEs), where each ACE
   specifies a principal and a set of privileges that are either granted
   or denied to that principal. When a principal submits an operation
   (such as an HTTP or WebDAV method) to a resource for execution, the
   server evaluates the ACEs in the ACL to determine if the principal
   has permission for that operation.

   Since every ACE contains the identifier of a principal, client
   software operated by a human must provide a mechanism for selecting
   this principal. This specification uses http(s) scheme URLs to
   identify principals, which are represented as WebDAV-
         capable WebDAV-capable
   resources. There is no guarantee that the URLs identifying principals
   will be meaningful to a human. For example,
         http://www.example.com/u/256432 http://www.example.com/u/
   256432 and http://www.example.com/people/Greg.Stein are both valid
   URLs that could be used to identify the same principal. To remedy
   this, every principal resource has the DAV:displayname property
   containing a human-readable name for the principal.

   Since a principal can be identified by multiple URLs, it raises the
   problem of determining exactly which principal is being referenced in
   a given ACE. It is impossible for a client to determine that an ACE
   granting the read privilege to
         http://www.example.com/people/Greg.Stein http://www.example.com/people/
   Greg.Stein also affects the principal at http://www.example.com/u/256432. http://www.example.com/u/
   256432. That is, a client has no mechanism for determining that two
   URLs identify the same principal resource.  As a result, this
   specification requires clients to use just one of the many possible
   URLs for a principal when creating ACEs. A client can discover which
   URL to use by retrieving the DAV:principal-URL property (Section 4.2)
   from a principal resource. No matter which of the principal's URLs is
   used with PROPFIND, the property always returns the same URL.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 4]

   With a system having hundreds to thousands of principals, the problem
   arises of how to allow a human operator of client software to select
   just one of these principals. One approach is to use broad collection
   hierarchies to spread the principals over a large number of
   collections, yielding few principals per collection. An example of
   this is a two level hierarchy with the first level containing 36
   collections (a-z, 0-9), and the second level being another 36,
   creating collections /a/a/, /a/b/, ..., /a/z/, such that a principal
   with last name "Stein" would appear at /s/t/Stein. In effect, this
   pre-computes a common query, search on last name, and encodes it into
   a hierarchy. The drawback with this scheme is that it handles only a
   small set of predefined queries, and drilling down through the
   collection hierarchy adds unnecessary steps (navigate down/up) when
   the user already knows the principal's name. While organizing
   principal URLs into a hierarchy is a valid namespace organization,
   users should not be forced to navigate this hierarchy to select a
   principal.

   This specification provides the capability to perform substring
   searches over a small set of properties on the resources representing
   principals. This permits searches based on last name, first name,
   user name, job title, etc. Two separate searches are supported, both
   via the REPORT method, one to search principal resources
   (DAV:principal-property-search, Section 9.4), the other to determine
   which properties may be searched at all
   (DAV:principal-search-property-set, Section 9.5).

   Once a principal has been identified in an ACE, a server evaluating
   that ACE must know the identity of the principal making a protocol
   request, and must validate that that principal is who they claim to
   be, a process known as authentication. This specification
   intentionally omits discussion of authentication, as the HTTP
   protocol already has a number of authentication mechanisms [RFC2617].
   Some authentication mechanism (such as HTTP Digest Authentication,
   which all WebDAV compliant implementations are required to support)
   must be available to validate the identity of a principal.

   The following issues are out of scope for this document:
           .

   o  Access control that applies only to a particular property on a
      resource (excepting the access control properties DAV:acl and
      DAV:current-user-privilege-set), rather than the entire resource,
           .

   o  Role-based security (where a role can be seen as a dynamically
      defined group of principals),
           .

   o  Specification of the ways an ACL on a resource is initialized,
           .

   o  Specification of an ACL that applies globally to all resources,
      rather than to a particular resource.
           .

   o  Creation and maintenance of resources representing people or
      computational agents (principals), and groups of these.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 5]

   This specification is organized as follows. Section 1.1 defines key
   concepts used throughout the specification, and is followed by a more
   in-depth discussion of principals (Section 2), and privileges
   (Section 3). Properties defined on principals are specified in
   Section 4, and access control properties for content resources are
   specified in Section 5. The ways ACLs are to be evaluated is
   described in section Section 6. Client discovery of access control capability
   using OPTIONS is described in Section 7.1. 7.2. Interactions between
   access control functionality and existing HTTP and WebDAV methods are
   described in the remainder of Section 7. The access control setting
   method, ACL, is specified in Section 8. Four reports that provide
   limited server-side searching capabilities are described in Section
   9. Sections on XML processing (Section 10), Internationalization
   considerations (Section 11), security considerations (Section 12),
   and authentication (Section 13) round out the specification. An
   appendix (Section 19.1) (Appendix A) provides an XML Document Type Definition (DTD)
   for the XML elements defined in the specification.

1.1 Terms

   This draft uses the terms defined in HTTP [RFC2616] and WebDAV
   [RFC2518].  In addition, the following terms are defined:

   principal

      A "principal" is a distinct human or computational actor that
      initiates access to network resources.  In this protocol, a
      principal is an HTTP resource that represents such an actor.

   group

      A "group" is a principal that represents a set of other
      principals.

   privilege

      A "privilege" controls access to a particular set of HTTP
      operations on a resource.

   aggregate privilege

      An "aggregate privilege" is a privilege that contains a set of
      other privileges.

   abstract privilege
      The modifier "abstract", when applied to a privilege on a
      resource, means the privilege cannot be set in an access control
      element (ACE) on that resource . resource.

   access control list (ACL)

      An "ACL" is a list of access control elements that define access
      control to a particular resource.

   access control element (ACE)

      An "ACE" either grants or denies a particular set of (non-
         abstract)
      (non-abstract) privileges for a particular principal.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 6]

   inherited ACE

      An "inherited ACE" is an ACE that is dynamically shared from the
      ACL of another resource. When a shared ACE changes on the primary
      resource, it is also changed on inheriting resources.

   protected property

      A "protected property" is one whose value cannot be updated except
      by a method explicitly defined as updating that specific property.
      In particular, a protected property cannot be updated with a
      PROPPATCH request.

1.2 Notational Conventions

   The augmented BNF used by this document to describe protocol elements
   is described in Section 2.1 of [RFC2616]. Because this augmented BNF
   uses the basic production rules provided in Section 2.2 of [RFC2616],
   those rules apply to this document as well.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   Definitions of XML elements in this document use XML element type
   declarations (as found in XML Document Type Declarations), described
   in Section 3.2 of [REC-XML]. When an XML element type in the "DAV:"
   namespace is referenced in this document outside of the context of an
   XML fragment, the string "DAV:" will be prefixed to the element name.

    2  PRINCIPALS

2. Principals

   A principal is a network resource that represents a distinct human or
   computational actor that initiates access to network resources. Users
   and groups are represented as principals in many implementations;
   other types of principals are also possible. A URI of any scheme MAY
   be used to identify a principal resource. However, servers
   implementing this specification MUST expose principal resources at an
   http(s) URL, which is a privileged scheme that points to resources
   that have additional properties, as described in Section 4. So, a
   principal resource can have multiple URIs, one of which has to be an
   http(s) scheme URL. Although an implementation SHOULD support
   PROPFIND and MAY support PROPPATCH to access and modify information
   about a principal, it is not required to do so.

   A principal resource may be a group, where a group is a principal
   that represents a set of other principals, called the members of the
   group.  If a person or computational agent matches a principal
   resource that is a member of a group, they also match the group.
   Membership in a group is recursive, so if a principal is a member of
   group GRPA, and GRPA is a member of group GRPB, then the principal is
   also a member of GRPB.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 7] 
    3  PRIVILEGES

3. Privileges

   Ability to perform a given method on a resource MUST be controlled by
   one or more privileges.  Authors of protocol extensions that define
   new HTTP methods SHOULD specify which privileges (by defining new
   privileges, or mapping to ones below) are required to perform the
   method.  A principal with no privileges to a resource MUST be denied
   any HTTP access to that resource, unless the principal matches an ACE
   constructed using the DAV:all, DAV:authenticated, or
   DAV:unauthenticated pseudo-principals (see Section 5.4.1). 5.5.1).  Servers
   MUST report a 403 "Forbidden" error if access is denied, except in
   the case where the privilege restricts the ability to know the
   resource exists, in which case 404 "Not Found" may be returned.

   Privileges may be containers of other privileges, in which case they
   are termed "aggregate privileges".  If a principal is granted or
   denied an aggregate privilege, it is semantically equivalent to
   granting or denying each of the aggregated privileges individually.
   For example, an implementation may define add-
         member add-member and
   remove-member privileges that control the ability to add and remove a
   member of a group.  Since these privileges control the ability to
   update the state of a group, these privileges would be aggregated by
   the DAV:write privilege on a group, and granting the DAV:write
   privilege on a group would also grant the add-member and
   remove-member privileges.

   Privileges may be declared to be "abstract" for a given resource, in
   which case they cannot be set in an ACE on that resource. Aggregate
   and non-aggregate privileges are both capable of being abstract.
   Abstract privileges are useful for modeling privileges that otherwise
   would not be exposed via the protocol. Abstract privileges also
   provide server implementations with flexibility in implementing the
   privileges defined in this specification.  For example, if a server
   is incapable of separating the read resource capability from the read
   ACL capability, it can still model the DAV:read and DAV:read-acl
   privileges defined in this specification by declaring them abstract,
   and containing them within a non-
         abstract non-abstract aggregate privilege (say,
   read-all) that holds DAV:read, and DAV:read-acl. In this way, it is
   possible to set the aggregate privilege, read-all, thus coupling the
   setting of DAV:read and DAV:read-acl, but it is not possible to set
   DAV:read, or DAV:read-
         acl DAV:read-acl individually. Since aggregate privileges
   can be abstract, it is also possible to use abstract privileges to
   group or organize non-abstract privileges. Privilege containment
   loops are not allowed; therefore, a privilege MUST NOT contain
   itself. For example, DAV:read cannot contain DAV:read.

   The set of privileges that apply to a particular resource may vary
   with the DAV:resourcetype of the resource, as well as between
   different server implementations.  To promote interoperability,
   however, this specification defines a set of well-known privileges
   (e.g. DAV:read, DAV:write, DAV:read-acl, DAV:write-acl, DAV:read-
         current-user-privilege-set,
   DAV:read-current-user-privilege-set, and DAV:all), which can at least
   be used to classify the other privileges defined on a particular

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 8]
   resource. The access permissions on null resources (defined in
   [RFC2518], Section 3) are solely those they inherit (if any), and
   they are not discoverable (i.e., the access control properties
   specified in Section 5 are not defined on null resources). On the
   transition from null to stateful resource, the initial access control
   list is set by the server's default ACL value policy (if any).

   Server implementations MAY define new privileges beyond those defined
   in this specification. Privileges defined by individual
   implementations MUST NOT use the DAV: namespace, and instead should
   use a namespace that they control, such as an http scheme URL.

3.1 DAV:read Privilege

   The read privilege controls methods that return information about the
   state of the resource, including the resource's properties. Affected
   methods include GET and PROPFIND.  Any implementation-
         defined implementation-defined
   privilege that also controls access to GET and PROPFIND must be
   aggregated under DAV:read¨if DAV:read - if an ACL grants access to DAV:read, the
   client may expect that no other privilege needs to be granted to have
   access to GET and PROPFIND.  Additionally, the read privilege MUST
   control the OPTIONS method.

   <!ELEMENT read EMPTY>

3.2 DAV:write Privilege

   The write privilege controls methods that lock a resource or modify
   the content, dead properties, or (in the case of a collection)
   membership of the resource, such as PUT and PROPPATCH. Note that
   state modification is also controlled via locking (see section 5.3 of [WEBDAV]),
   [RFC2518]), so effective write access requires that both write
   privileges and write locking requirements are satisfied.  Any
   implementation-defined privilege that also controls access to methods
   modifying content, dead properties or collection membership must be
   aggregated under DAV:write, e.g. if an ACL grants access to
   DAV:write, the client may expect that no other privilege needs to be
   granted to have access to PUT and PROPPATCH.

   <!ELEMENT write EMPTY>

3.3 DAV:write-properties Privilege

   The DAV:write-properties privilege controls methods that modify the
   dead properties of the resource, such as PROPPATCH.  Whether this
   privilege may be used to control access to any live properties is
   determined by the implementation.  Any implementation-defined
   privilege that also controls access to methods modifying dead
   properties must be aggregated under
         DAV:write-properties¨e.g. DAV:write-properties - e.g. if an
   ACL grants access to DAV:write-
         properties, DAV:write-properties, the client can safely
   expect that no other privilege needs to be granted to have access to
   PROPPATCH.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 9]

   <!ELEMENT write-properties EMPTY>

3.4 DAV:write-content Privilege

   The DAV:write-content privilege controls methods that modify the
   content or (in the case of a collection) membership of the an existing resource, such as PUT and DELETE. PUT.  Any
   implementation-defined privilege that also controls access to content or alteration of
         collection membership
   must be aggregated under DAV:write-content¨ DAV:write-content - e.g. if an ACL grants
   access to DAV:write-content, the client can safely expect that no
   other privilege needs to be granted to have access to PUT. Note that
   PUT or DELETE. - when applied to an unmapped URI - creates a new resource and
   therefore is controlled by the DAV:bind privilege on the parent
   collection.

   <!ELEMENT write-content EMPTY>

3.5 DAV:unlock Privilege

   The DAV:unlock privilege controls the use of the UNLOCK method by a
   principal other than the lock owner (the principal that created a
   lock can always perform an UNLOCK).  While the set of users who may
   lock a resource is most commonly the same set of users who may modify
   a resource, servers may allow various kinds of administrators to
   unlock resources locked by others. Any privilege controlling access
   by non-lock owners to UNLOCK MUST be aggregated under DAV:unlock.

   A lock owner can always remove a lock by issuing an UNLOCK with the
   correct lock token and authentication credentials. That is, even if a
   principal does not have DAV:unlock privilege, they can still remove
   locks they own. Principals other than the lock owner can remove a
   lock only if they have DAV:unlock privilege and they issue an UNLOCK
   with the correct lock token. Lock timeout is not affected by the
   DAV:unlock privilege.

   <!ELEMENT unlock EMPTY>

3.6 DAV:read-acl Privilege

   The DAV:read-acl privilege controls the use of PROPFIND to retrieve
   the DAV:acl property of the resource.

   <!ELEMENT read-acl EMPTY>

3.7 DAV:read-current-user-privilege-set Privilege

   The DAV:read-current-user-privilege-set privilege controls the use of
   PROPFIND to retrieve the DAV:current-user-privilege-set property of
   the resource.

   Clients are intended to use this property to visually indicate in
   their UI items that are dependent on the permissions of a resource,
   for example, by graying out resources that are not writeable.

   This privilege is separate from DAV:read-acl because there is a need
   to allow most users access to the privileges permitted the current
   user (due to its use in creating the UI), while the full

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 10] ACL contains
   information that may not be appropriate for the current authenticated
   user. As a result, the set of users who can view the full ACL is
   expected to be much smaller than those who can read the current user
   privilege set, and hence distinct privileges are needed for each.

   <!ELEMENT read-current-user-privilege-set EMPTY>

3.8 DAV:write-acl Privilege

   The DAV:write-acl privilege controls use of the ACL method to modify
   the DAV:acl property of the resource.

   <!ELEMENT write-acl EMPTY>

3.9 DAV:bind Privilege

   The DAV:bind privilege allows a method to add a new member URL to the
   specified collection (for example via PUT or MKCOL).  It is ignored
   for resources that are not collections.

   <!ELEMENT bind EMPTY>

    3.10DAV:unbind

3.10 DAV:unbind Privilege

   The DAV:unbind privilege allows a method to remove a member URL from
   the specified collection (for example via DELETE or MOVE). It is
   ignored for resources that are not collections.

   <!ELEMENT unbind EMPTY>

3.11 DAV:all Privilege

   DAV:all is an aggregate privilege that contains the entire set of
   privileges that can be applied to the resource.

   <!ELEMENT all EMPTY>

3.12 Aggregation of Predefined Privileges

   Server implementations are free to aggregate the predefined
   privileges (defined above in Sections 3.1-3.9) 3.1-3.10) subject to the
   following limitations:

   DAV:read-acl MUST NOT contain DAV:read, DAV:write, DAV:write-acl,
   DAV:write-properties, DAV:write-content, or DAV:read-current-user-
         privilege-set.
   DAV:read-current-user-privilege-set.

   DAV:write-acl MUST NOT contain DAV:write, DAV:read, DAV:read-acl, or
   DAV:read-current-user-privilege-set.

   DAV:read-current-user-privilege-set MUST NOT contain DAV:write,
   DAV:read, DAV:read-acl, or DAV:write-acl.

   DAV:write MUST NOT contain DAV:read, DAV:read-acl, or DAV:read-
         current-user-privilege-set.
   DAV:read-current-user-privilege-set.

   DAV:read MUST NOT contain DAV:write, DAV:write-acl, DAV:write-
         properties,
   DAV:write-properties, or DAV:write-content.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 11]

   DAV:write MUST contain DAV:bind, DAV:unbind, DAV:write-properties and
   DAV:write-content.

    4  PRINCIPAL PROPERTIES

4. Principal Properties

   Principals are manifested to clients as a WebDAV resource, identified
   by a URL.  A principal MUST have a non-empty DAV:displayname property
   (defined in Section 13.2 of [RFC2518]), and a DAV:resourcetype
   property (defined in Section 13.9 of [RFC2518]).  Additionally, a
   principal MUST report the DAV:principal XML element in the value of
   the DAV:resourcetype property.  The element type declaration for
   DAV:principal is:

   <!ELEMENT principal EMPTY>

   This protocol defines the following additional properties for a
   principal. Since it can be expensive for a server to retrieve access
   control information, the name and value of these properties SHOULD
   NOT be returned by a PROPFIND allprop request (as defined in Section
   12.14.1 of [RFC2518]).

4.1 DAV:alternate-URI-set

   This protected property, if non-empty, contains the URIs of network
   resources with additional descriptive information about the
   principal. This property identifies additional network resources
   (i.e., it contains one or more URIs) that may be consulted by a
   client to gain additional knowledge concerning a principal. One
   expected use for this property is the storage of an LDAP [RFC2255]
   scheme URL. A user-agent encountering an LDAP URL could use LDAP [RFC2589]
   [RFC2251] to retrieve additional machine-readable directory
   information about the principal, and display that information in its
   user interface. Support for this property is REQUIRED, and the value
   is empty if no alternate URI exists for the principal.

   <!ELEMENT alternate-URI-set (href*)>

4.2 DAV:principal-URL

   A principal may have many URLs, but there must be one "principal URL"
   that clients can use to uniquely identify a principal.  This
   protected property contains the URL that MUST be used to identify
   this principal in an ACL request. Support for this property is
   REQUIRED.

   <!ELEMENT principal-URL (href)>

4.3 DAV:group-member-set

   This property of a group principal identifies the principals that are
   direct members of this group. Since a group may be a member of
   another group, a group may also have indirect members (i.e. the
   members of its direct members).  A URL in the DAV:group-member-set
   for a principal MUST be the DAV:principal-URL of that principal.

   <!ELEMENT group-member-set (href*)>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 12]

4.4 DAV:group-membership

   This protected property identifies the groups in which the principal
   is directly a member.  Note that a server may allow a group to be a
   member of another group, in which case the DAV:group-membership of
   those other groups would need to be queried in order to determine the
   groups in which the principal is indirectly a member. Support for
   this property is REQUIRED.

   <!ELEMENT group-membership (href*)>

    5  ACCESS CONTROL PROPERTIES

5. Access Control Properties

   This specification defines a number of new properties for WebDAV
   resources.  Access control properties may be retrieved just like
   other WebDAV properties, using the PROPFIND method.  Since it is
   expensive, for many servers, to retrieve access control information,
   a PROPFIND allprop request (as defined in Section 12.14.1 of
   [RFC2518]) SHOULD NOT return the names and values of the properties
   defined in this section.

   Access control properties (especially DAV:acl and DAV:inherited-
         acl-set)
   DAV:inherited-acl-set) are defined on the resource identified by the
   Request-URI of a PROPFIND request. A direct consequence is that if
   the resource is accessible via multiple URI, the value of access
   control properties is the same across these URI.

   HTTP resources that support the WebDAV Access Control Protocol MUST
   contain the following properties. Null resources (described in
   Section 3 of [RFC2518]) MUST NOT contain the following properties.

5.1 DAV:owner

   This protected  property identifies a particular principal as being the "owner"
   of the resource. Since the owner of a resource often has special
   access control capabilities (e.g., the owner frequently has permanent
   DAV:write-acl privilege), clients might display the resource owner in
   their user interface.

   Servers MAY implement DAV:owner as protected property and MAY return
   an empty DAV:owner element as property value in case no owner
   information is available.

   <!ELEMENT owner (href)> (href?)>

5.1.1 Example: Retrieving DAV:owner

   This example shows a client request for the value of the DAV:owner
   property from a collection resource with URL
         http://www.example.com/papers/. http://www.example.com/
   papers/. The principal making the request is authenticated using
   Digest authentication. The value of DAV:owner is the URL http://www.example.com/acl/users/gstein, http://
   www.example.com/acl/users/gstein, wrapped in the DAV:href XML
   element.

   >> Request <<

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 13]

   PROPFIND /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="jim",
            realm="jim@webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:owner/>
     </D:prop>
   </D:propfind>
   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/papers/</D:href>
       <D:propstat>
         <D:prop>
           <D:owner>
             <D:href>http://www.example.com/acl/users/gstein</D:href>
           </D:owner>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

5.1.2 Example: An Attempt to Set DAV:owner

   The following example shows a client request to modify the value of
   the DAV:owner property on the resource with URL
         <http://www.example.com/papers>. <http://
   www.example.com/papers>. Since DAV:owner is a protected
         property, the server property on
   this particular server, it responds with a 207 (Multi-Status)
   response that contains a 403 (Forbidden) status code for the act of
   setting DAV:owner. Section 8.2.1 of [RFC2518] describes PROPPATCH
   status code information, and  Section 11 of [RFC2518] describes the Multi-
         Status response.
   Multi-Status response and Sections 1.6 and 3.12 of [RFC3253] describe
   additional error marshalling for PROPPATCH attempts on protected
   properties.

   >> Request <<

   PROPPATCH /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 14]
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="jim",
            realm="jim@webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propertyupdate xmlns:D="DAV:">
     <D:set>
       <D:prop>
         <D:owner>
           <D:href>http://www.example.com/acl/users/jim</D:href>
         </D:owner>
       </D:prop>
     </D:set>
   </D:propertyupdate>

   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/papers/</D:href>
       <D:propstat>
         <D:prop><D:owner/></D:prop>
         <D:status>HTTP/1.1 403 Forbidden</D:status>
         <D:responsedescription>
           <D:error><D:cannot-modify-protected-property/></D:error>
           Failure to set protected property (DAV:owner)
         </D:responsedescription>
       </D:propstat>
     </D:response>
   </D:multistatus>

5.2 DAV:group

   This property identifies a particular principal as being the "group"
   of the resource. This property is commonly found on repositories that
   implement the Unix privileges model.

   Servers MAY implement DAV:group as protected property and MAY return
   an empty DAV:group element as property value in case no group
   information is available.

   <!ELEMENT group (href?)>

5.3 DAV:supported-privilege-set

   This is a protected property that identifies the privileges defined
   for the resource.

   <!ELEMENT supported-privilege-set (supported-privilege*)>

   Each privilege appears as an XML element, where aggregate privileges
   list as sub-elements all of the privileges that they aggregate.

   <!ELEMENT supported-privilege
    (privilege, abstract?, description, supported-privilege*)>
   <!ELEMENT privilege ANY>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 15]

   An abstract privilege MUST NOT be used in an ACE for that resource.
   Servers MUST fail an attempt to set an abstract privilege.

   <!ELEMENT abstract EMPTY>

   A description is a human-readable description of what this privilege
   controls access to. Servers MUST indicate the human language of the
   description using the xml:lang attribute and SHOULD consider the HTTP
   Accept-Language request header when selecting one of multiple
   available languages.

   <!ELEMENT description #PCDATA>

   It is envisioned that a WebDAV ACL-aware administrative client would
   list the supported privileges in a dialog box, and allow the user to
   choose non-abstract privileges to apply in an ACE.  The privileges
   tree is useful programmatically to map well-known privileges (defined
   by WebDAV or other standards groups) into privileges that are
   supported by any particular server implementation.  The privilege
   tree also serves to hide complexity in implementations allowing large
   number of privileges to be defined by displaying aggregates to the
   user.

    5.2.1

5.3.1 Example: Retrieving a List of Privileges Supported on a Resource

   This example shows a client request for the DAV:supported-
         privilege-set
   DAV:supported-privilege-set property on the resource
         http://www.example.com/papers/. http://
   www.example.com/papers/. The value of the DAV:supported-
         privilege-set DAV:supported-privilege-set
   property is a tree of supported privileges (using "[XML Namespace ,
   localname]" to identify each privilege):

     [DAV:, all] (aggregate, abstract)
        |
        +-- [DAV:, read] (aggregate)
               |
               +-- [DAV:, read-acl] (abstract)
               +-- [DAV:, read-current-user-privilege-set] (abstract)
        |
        +-- [DAV:, write] (aggregate)
               |
               +-- [DAV:, write-acl] (abstract)
               +-- [DAV:, write-properties]
               +-- [DAV:, write-content]
        |
        +-- [DAV:, unlock]

   This privilege tree is not normative (except that it reflects the
   normative aggregation rules given in Section 3.12), and many possible
   privilege trees are possible.

   >> Request <<

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 16]

   PROPFIND /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="gclemm",
            realm="gclemm@webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:supported-privilege-set/>
     </D:prop>
   </D:propfind>

   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/papers/</D:href>
       <D:propstat>
         <D:prop>
           <D:supported-privilege-set>
             <D:supported-privilege>
                     <D:privilege> <D:all/> </D:privilege>
               <D:privilege><D:all/></D:privilege>
              <D:abstract/>
               <D:description xml:lang="en">
                 Any operation</D:description> operation
               </D:description>
               <D:supported-privilege>
                       <D:privilege> <D:read/> </D:privilege>
                 <D:privilege><D:read/></D:privilege>
                 <D:description xml:lang="en">
                   Read any object</D:description> object
                 </D:description>
                 <D:supported-privilege>
                         <D:privilege> <D:read-acl/> </D:privilege>
                   <D:privilege><D:read-acl/></D:privilege>
                   <D:abstract/>
                         <D:description xml:lang="en">
                           Read
                   <D:description xml:lang="en">Read ACL</D:description>
                 </D:supported-privilege>
                 <D:supported-privilege>
                   <D:privilege>
                     <D:read-current-user-privilege-set/>
                   </D:privilege>
                   <D:abstract/>
                   <D:description xml:lang="en">
                     Read current user privilege set property
                   </D:description>
                 </D:supported-privilege>
               </D:supported-privilege>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 17]
               <D:supported-privilege>
                       <D:privilege> <D:write/> </D:privilege>
                 <D:privilege><D:write/></D:privilege>
                 <D:description xml:lang="en">
                   Write any object</D:description> object
                 </D:description>
                 <D:supported-privilege>
                         <D:privilege> <D:write-acl/> </D:privilege>
                   <D:privilege><D:write-acl/></D:privilege>
                   <D:description xml:lang="en">
                     Write ACL</D:description> ACL
                   </D:description>
                   <D:abstract/>
                 </D:supported-privilege>
                 <D:supported-privilege>
                         <D:privilege> <D:write-properties/> </D:privilege>
                   <D:privilege><D:write-properties/></D:privilege>
                   <D:description xml:lang="en">
                     Write properties</D:description> properties
                   </D:description>
                 </D:supported-privilege>
                 <D:supported-privilege>
                         <D:privilege> <D:write-content/> </D:privilege>
                   <D:privilege><D:write-content/></D:privilege>
                   <D:description xml:lang="en">
                     Write resource content</D:description> content
                   </D:description>
                 </D:supported-privilege>
               </D:supported-privilege>
               <D:supported-privilege>
                         <D:privilege> <D:unlock/> </D:privilege>
                 <D:privilege><D:unlock/></D:privilege>
                 <D:description xml:lang="en">
                   Unlock resource</D:description> resource
                 </D:description>
               </D:supported-privilege>
             </D:supported-privilege>
           </D:supported-privilege-set>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

    5.3

5.4 DAV:current-user-privilege-set

   DAV:current-user-privilege-set is a protected property containing the
   exact set of privileges (as computed by the server) granted to the
   currently authenticated HTTP user. Aggregate privileges and their
   contained privileges are listed. A user-agent can use the value of
   this property to adjust its user interface to make actions
   inaccessible (e.g., by graying out a menu item or button) for which
   the current principal does not have permission. This property is also
   useful for determining what operations the current principal can
   perform, without having to actually execute an operation.

   <!ELEMENT current-user-privilege-set (privilege*)>
   <!ELEMENT privilege ANY>

   If the current user is granted a specific privilege, that privilege
   must belong to the set of privileges that may be set on this
   resource. Therefore, each element in the DAV:current-user-

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 18] 
         privilege-set
   DAV:current-user-privilege-set property MUST identify a non-abstract
   privilege from the DAV:supported-privilege-set property.

    5.3.1

5.4.1 Example: Retrieving the User's Current Set of Assigned Privileges

   Continuing the example from Section 5.2.1, 5.3.1, this example shows a
   client requesting the DAV:current-user-privilege-set property from
   the resource with URL http://www.example.com/papers/. The username of
   the principal making the request is "khare", and Digest
   authentication is used in the request. The principal with username
   "khare" has been granted the DAV:read privilege. Since the DAV:read
   privilege contains the DAV:read-acl and DAV:read-current-
         user-privilege-set
   DAV:read-current-user-privilege-set privileges (see Section 5.2.1), 5.3.1),
   the principal with username "khare" can read the ACL property, and
   the DAV:current-user-privilege-set property. However, the DAV:all,
   DAV:read-acl, DAV:write-acl and DAV:read-current-user-privilege-
         set DAV:read-current-user-privilege-set
   privileges are not listed in the value of DAV:current-user-
         privilege-set,
   DAV:current-user-privilege-set, since (for this example) they are
   abstract privileges. DAV:write is not listed since the principal with
   username "khare" is not listed in an ACE granting that principal
   write permission.

   >> Request <<

   PROPFIND /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="khare",
            realm="khare@webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:current-user-privilege-set/>
     </D:prop>
   </D:propfind>
   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
     <D:href>http://www.example.com/papers/</D:href>
     <D:propstat>
       <D:prop>
         <D:current-user-privilege-set>
                   <D:privilege> <D:read/> </D:privilege>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 19]
           <D:privilege><D:read/></D:privilege>
         </D:current-user-privilege-set>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
     </D:response>
   </D:multistatus>

    5.4

5.5 DAV:acl

   This is a protected property that specifies the list of access
   control entries (ACEs), which define what principals are to get what
   privileges for this resource.

   <!ELEMENT acl (ace*) >

   Each DAV:ace element specifies the set of privileges to be either
   granted or denied to a single principal.  If the DAV:acl property is
   empty, no principal is granted any privilege.

   <!ELEMENT ace ((principal | invert), (grant|deny), protected?,
                  inherited?)>

    5.4.1

5.5.1 ACE Principal

   The DAV:principal element identifies the principal to which this ACE
   applies.

   <!ELEMENT principal (href | all | authenticated | unauthenticated
    | property | self)>

   The current user matches DAV:href only if that user is authenticated
   as being (or being a member of) the principal identified by the URL
   contained by that DAV:href.

   The current user always matches DAV:all.

   <!ELEMENT all EMPTY>

   The current user matches DAV:authenticated only if authenticated.

   <!ELEMENT authenticated EMPTY>

   The current user matches DAV:unauthenticated only if not
   authenticated.

   <!ELEMENT unauthenticated EMPTY>

   DAV:all is the union of DAV:authenticated, and DAV:unauthenticated.
   For a given request, the user matches either DAV:authenticated, or
   DAV:unauthenticated, but not both (that is, DAV:authenticated and
   DAV:unauthenticated are disjoint sets).

   The current user matches a DAV:property principal in a DAV:acl
   property of a resource only if the value of the identified property
   of that resource contains at most one DAV:href XML

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 20] element, the URI
   value of DAV:href identifies a principal, and the current user is
   authenticated as being (or being a member of) that principal.  For
   example, if the DAV:property element contained <DAV:owner/>, the
   current user would match the DAV:property principal only if the
   current user is authenticated as matching the principal identified by
   the DAV:owner property of the resource.

   <!ELEMENT property ANY>

   The current user matches DAV:self in a DAV:acl property of the
   resource only if that resource is a principal and that principal
   matches the current user or, if the principal is a group, a member of
   that group matches the current user.

   <!ELEMENT self EMPTY>

   Some servers may support ACEs applying to those users NOT matching
   the current principal, e.g. all users not in a particular group.
   This can be done by wrapping the DAV:principal element with
   DAV:invert.

   <!ELEMENT invert principal>

    5.4.2

5.5.2 ACE Grant and Deny

   Each DAV:grant or DAV:deny element specifies the set of privileges to
   be either granted or denied to the specified principal.  A DAV:grant
   or DAV:deny element of the DAV:acl of a resource MUST only contain
   non-abstract elements specified in the DAV:supported-
         privilege-set DAV:supported-privilege-set of
   that resource.

   <!ELEMENT grant (privilege+)>
   <!ELEMENT deny (privilege+)>
   <!ELEMENT privilege ANY>

    5.4.3

5.5.3 ACE Protection

   A server indicates an ACE is protected by including the DAV:protected
   element in the ACE. If the ACL of a resource contains an ACE with a
   DAV:protected element, an attempt to remove that ACE from the ACL
   MUST fail.

   <!ELEMENT protected EMPTY>

    5.4.4

5.5.4 ACE Inheritance

   The presence of a DAV:inherited element indicates that this ACE is
   inherited from another resource that is identified by the URL
   contained in a DAV:href element.  An inherited ACE cannot be modified
   directly, but instead the ACL on the resource from which it is
   inherited must be modified.

   Note that ACE inheritance is not the same as ACL initialization. ACL
   initialization defines the ACL that a newly created resource

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 21] will use
   (if not specified).  ACE inheritance refers to an ACE that is
   logically shared - where an update to the resource containing an ACE
   will affect the ACE of each resource that inherits that ACE.  The
   method by which ACLs are initialized or by which ACEs are inherited
   is not defined by this document.

   <!ELEMENT inherited (href)>

    5.4.5

5.5.5 Example: Retrieving a Resource's Access Control List

   Continuing the example from Sections 5.2.1 5.3.1 and 5.3.1, 5.4.1, this example
   shows a client requesting the DAV:acl property from the resource with
   URL http://www.example.com/papers/. There are two ACEs defined in
   this ACL:

   ACE #1: The group identified by URL
         http://www.example.com/acl/groups/maintainers http://www.example.com/acl/
   groups/maintainers (the group of site maintainers) is granted
   DAV:write privilege. Since (for this example) DAV:write contains the
   DAV:write-acl privilege (see Section 5.2.1), 5.3.1), this means the
   "maintainers" group can also modify the access control list.

   ACE #2: All principals (DAV:all) are granted the DAV:read privilege.
   Since (for this example) DAV:read contains DAV:read-acl and
   DAV:read-current-user-privilege-set, this means all users (including
   all members of the "maintainers" group) can read the DAV:acl property
   and the DAV:current-user-privilege-set property.

   >> Request <<

   PROPFIND /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="masinter",
            realm="webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:acl/>
     </D:prop>
   </D:propfind>
   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/papers/</D:href>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 22]
       <D:propstat>
         <D:prop>
           <D:acl>
           <D:ace>
             <D:principal>
         <D:href>http://www.example.com/acl/groups/maintainers</D:href>
               <D:href
               >http://www.example.com/acl/groups/maintainers</D:href>
             </D:principal>
             <D:grant>
                       <D:privilege> <D:write/> </D:privilege>
               <D:privilege><D:write/></D:privilege>
             </D:grant>
           </D:ace>
           <D:ace>
             <D:principal>
               <D:all/>
             </D:principal>
             <D:grant>
                       <D:privilege> <D:read/> </D:privilege>
               <D:privilege><D:read/></D:privilege>
             </D:grant>
           </D:ace>
         </D:acl>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

    5.5 DAV: acl-restrictions

5.6 DAV:acl-restrictions

   This protected property defines the types of ACLs supported by this
   server, to avoid clients needlessly getting errors.  When a client
   tries to set an ACL via the ACL method, the server may reject the
   attempt to set the ACL as specified.  The following properties
   indicate the restrictions the client must observe before setting an
   ACL:

   <grant-only> Deny ACEs are not supported

   <no-invert> Inverted ACEs are not supported

   <deny-before-grant> All deny ACEs must occur before any grant ACEs

   <required-principal> Indicates which principals are required to be
      present

   <!ELEMENT acl-restrictions (grant-only?, no-invert?, deny-before-
         grant?,
                               deny-before-grant?,
                               required-principal?)>

    5.5.1

5.6.1 DAV:grant-only

   This element indicates that ACEs with deny clauses are not allowed.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 23]

   <!ELEMENT grant-only EMPTY>

    5.5.2

5.6.2 DAV:no-invert ACE Constraint

   This element indicates that ACEs with the <invert> element are not
   allowed.

   <!ELEMENT no-invert EMPTY>

    5.5.3

5.6.3 DAV:deny-before-grant

   This element indicates that all deny ACEs must precede all grant
   ACEs.

   <!ELEMENT deny-before-grant EMPTY>

    5.5.4

5.6.4 Required Principals

   The required principal elements identify which principals must have
   an ACE defined in the ACL.

   <!ELEMENT required-principal
     (all? | authenticated? | unauthenticated? | self? | href* |
      property*)>

   For example, the following element requires that the ACL contain a
   DAV:owner property ACE:

   <D:required-principal xmlns:D="DAV:">
           <D:property> <D:owner/> </D:property>
     <D:property><D:owner/></D:property>
   </D:required-principal>

5.6.5 Example: Retrieving DAV:acl-restrictions

   In this example, the client requests the value of the DAV:acl-
         restrictions
   DAV:acl-restrictions property. Digest authentication provides
   credentials for the principal operating the client.

   >> Request <<

   PROPFIND /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="srcarter",
            realm="srcarter@webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:acl-restrictions/>
     </D:prop>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 24]
   </D:propfind>
   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/papers/</D:href>
       <D:propstat>
         <D:prop>
           <D:acl-restrictions>
             <D:grant-only/>
             <D:required-principal>
               <D:all/>
             </D:required-principal>
           </D:acl-restrictions>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
           <D:response>
     </D:response>
   </D:multistatus>

    5.6

5.7 DAV:inherited-acl-set

   This protected property contains a set of URLs that identify other
   resources that also control the access to this resource.  To have a
   privilege on a resource, not only must the ACL on that resource
   (specified in the DAV:acl property of that resource) grant the
   privilege, but so must the ACL of each resource identified in the
   DAV:inherited-acl-set property of that resource.  Effectively, the
   privileges granted by the current ACL are ANDed with the privileges
   granted by each inherited ACL.

   <!ELEMENT inherited-acl-set (href*)>

    5.7

5.8 DAV:principal-collection-set

   This protected property of a resource contains a set of URLs that
   identify the root collections that contain the principals that are
   available on the server that implements this resource.  A WebDAV
   Access Control Protocol user agent could use the contents of
   DAV:principal-collection-set to retrieve the DAV:displayname property
   (specified in Section 13.2 of [RFC2518]) of all principals on that
   server, thereby yielding human-readable names for each principal that
   could be displayed in a user interface.

   <!ELEMENT principal-collection-set (href*)>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 25]

   Since different servers can control different parts of the URL
   namespace, different resources on the same host MAY have different
   DAV:principal-collection-set values. The collections specified in the
   DAV:principal-collection-set MAY be located on different hosts from
   the resource. The URLs in DAV:principal-collection-set SHOULD be http
   or https scheme URLs. For security and scalability reasons, a server
   MAY report only a subset of the entire set of known principal
   collections, and therefore clients should not assume they have
   retrieved an exhaustive listing. Additionally, a server MAY elect to
   report none of the principal collections it knows about, in which
   case the property value would be empty.

   The value of DAV:principal-collection-set gives the scope of the
   DAV:principal-property-search REPORT (defined in Section 9.4).
   Clients use the DAV:principal-property-search REPORT to populate
   their user interface with a list of principals. Therefore, servers
   that limit a client's ability to obtain principal information will
   interfere with the client's ability to manipulate access control
   lists, due to the difficulty of getting the URL of a principal for
   use in an ACE.

    5.7.1

5.8.1 Example: Retrieving DAV:principal-collection-set

   In this example, the client requests the value of the
   DAV:principal-collection-set property on the collection resource
   identified by URL http://www.example.com/papers/. The property
   contains the two URLs, http://www.example.com/acl/users/ and
         http://www.example.com/acl/groups/, http://
   www.example.com/acl/groups/, both wrapped in DAV:href XML elements.
   Digest authentication provides credentials for the principal
   operating the client.

   The client might reasonably follow this request with two separate
   PROPFIND requests to retrieve the DAV:displayname property of the
   members of the two collections (/acl/users and /acl/groups). This
   information could be used when displaying a user interface for
   creating access control entries.

   >> Request <<

   PROPFIND /papers/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="yarong",
            realm="yarong@webdav.org",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:principal-collection-set/>
     </D:prop>
   </D:propfind>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 26]

   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/papers/</D:href>
       <D:propstat>
         <D:prop>
           <D:principal-collection-set>
             <D:href>http://www.example.com/acl/users/</D:href>
             <D:href>http://www.example.com/acl/groups/</D:href>
           </D:principal-collection-set>
         </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

    5.8

5.9 Example: PROPFIND to retrieve access control properties

   The following example shows how access control information can be
   retrieved by using the PROPFIND method to fetch the values of the
   DAV:owner, DAV:supported-privilege-set, DAV:current-user-
         privilege-set,
   DAV:current-user-privilege-set, and DAV:acl properties.

   >> Request <<

   PROPFIND /top/container/ HTTP/1.1
   Host: www.example.com
   Content-type: text/xml; charset="utf-8"
   Content-Length: xxx
   Depth: 0
   Authorization: Digest username="ejw",
            realm="users@foo.org",
     realm="users@example.com", nonce="...",
     uri="/top/container/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:propfind xmlns:D="DAV:">
     <D:prop>
       <D:owner/>
       <D:supported-privilege-set/>
       <D:current-user-privilege-set/>
       <D:acl/>
     </D:prop>
   </D:propfind>

   >> Response <<

   HTTP/1.1 207 Multi-Status

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 27]
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:"
                  xmlns:A="http://www.example.com/acl/">
     <D:response>
       <D:href>http://www.example.com/top/container/</D:href>
       <D:propstat>
         <D:prop>
           <D:owner>
             <D:href>http://www.example.com/users/gclemm</D:href>
           </D:owner>
           <D:supported-privilege-set>
             <D:supported-privilege>
                 <D:privilege> <D:all/> </D:privilege>
               <D:privilege><D:all/></D:privilege>
               <D:abstract/>
               <D:description xml:lang="en">Any operation</D:description> xml:lang="en">
                 Any operation
               </D:description>
               <D:supported-privilege>
                   <D:privilege> <D:read/> </D:privilege>
                 <D:privilege><D:read/></D:privilege>
                 <D:description xml:lang="en">Read xml:lang="en">
                   Read any
         object</D:description> object
                 </D:description>
               </D:supported-privilege>
               <D:supported-privilege>
                   <D:privilege> <D:write/> </D:privilege>
                 <D:privilege><D:write/></D:privilege>
                 <D:abstract/>
                 <D:description xml:lang="en">Write xml:lang="en">
                   Write any
         object</D:description> object
                 </D:description>
                 <D:supported-privilege>
                     <D:privilege> <A:create/> </D:privilege>
                   <D:privilege><A:create/></D:privilege>
                   <D:description xml:lang="en">Create xml:lang="en">
                     Create an
         object</D:description> object
                   </D:description>
                 </D:supported-privilege>
                 <D:supported-privilege>
                     <D:privilege> <A:update/> </D:privilege>
                   <D:privilege><A:update/></D:privilege>
                   <D:description xml:lang="en">Update xml:lang="en">
                     Update an
         object</D:description> object
                   </D:description>
                 </D:supported-privilege>
               </D:supported-privilege>
               <D:supported-privilege>
                     <D:privilege> <A:unbind/> </D:privilege>
                 <D:privilege><A:delete/></D:privilege>
                 <D:description xml:lang="en">Remove binding to xml:lang="en">
                   Delete an
         object</D:description>
                   </D:supported-privilege> object
                 </D:description>
               </D:supported-privilege>
               <D:supported-privilege>
                   <D:privilege> <D:read-acl/> </D:privilege>
                 <D:privilege><D:read-acl/></D:privilege>
                 <D:description xml:lang="en">Read xml:lang="en">
                   Read the
         ACL</D:description> ACL
                 </D:description>
               </D:supported-privilege>
               <D:supported-privilege>
                   <D:privilege> <D:write-acl/> </D:privilege>
                 <D:privilege><D:write-acl/></D:privilege>
                 <D:description xml:lang="en">Write xml:lang="en">
                   Write the
         ACL</D:description> ACL
                 </D:description>
               </D:supported-privilege>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 28]
             </D:supported-privilege>
           </D:supported-privilege-set>
           <D:current-user-privilege-set>
               <D:privilege> <D:read/> </D:privilege>
               <D:privilege> <D:read-acl/> </D:privilege>
             <D:privilege><D:read/></D:privilege>
             <D:privilege><D:read-acl/></D:privilege>
           </D:current-user-privilege-set>
           <D:acl>
             <D:ace>
               <D:principal>
                 <D:href>http://www.example.com/users/esedlar</D:href>
               </D:principal>
               <D:grant>
                   <D:privilege> <D:read/> </D:privilege>
                   <D:privilege> <D:write/> </D:privilege>
                   <D:privilege> <D:read-acl/> </D:privilege>
                 <D:privilege><D:read/></D:privilege>
                 <D:privilege><D:write/></D:privilege>
                 <D:privilege><D:read-acl/></D:privilege>
               </D:grant>
             </D:ace>
             <D:ace>
               <D:principal>
                 <D:href>http://www.example.com/groups/marketing</D:href>
               </D:principal>
               <D:deny>
                   <D:privilege> <D:read/> </D:privilege>
                 <D:privilege><D:read/></D:privilege>
               </D:deny>
             </D:ace>
             <D:ace>
               <D:principal>
                   <D:property> <D:owner/> </D:property>
                 <D:property><D:owner/></D:property>
               </D:principal>
               <D:grant>
                   <D:privilege> <D:read-acl/> </D:privilege>
                   <D:privilege> <D:write-acl/> </D:privilege>
                 <D:privilege><D:read-acl/></D:privilege>
                 <D:privilege><D:write-acl/></D:privilege>
               </D:grant>
             </D:ace>
             <D:ace>
                 <D:principal> <D:all/> </D:principal>
               <D:principal><D:all/></D:principal>
               <D:grant>
                   <D:privilege> <D:read/> </D:privilege></D:grant>
                 <D:privilege><D:read/></D:privilege>
               </D:grant>
               <D:inherited>
                 <D:href>http://www.example.com/top</D:href>
               </D:inherited>
             </D:ace>
           </D:acl>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

   The value of the DAV:owner property is a single DAV:href XML element
   containing the URL of the principal that owns this resource.

   The value of the DAV:supported-privilege-set property is a tree of
   supported privileges (using "[XML Namespace , localname]" to identify
   each privilege):

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 29]

   [DAV:, all] (aggregate, abstract)
      |
      +-- [DAV:, read]
      +-- [DAV:, write] (aggregate, abstract)
             |
             +-- [http://www.example.com/acl, create]
             +-- [http://www.example.com/acl, update]
             +-- [http://www.example.com/acl, delete]
      +-- [DAV:, read-acl]
      +-- [DAV:, write-acl]

   The DAV:current-user-privilege-set property contains two privileges,
   DAV:read, and DAV:read-acl. This indicates that the current
   authenticated user only has the ability to read the resource, and
   read the DAV:acl property on the resource. The DAV:acl property
   contains a set of four ACEs:

   ACE #1: The principal identified by the URL
         http://www.example.com/users/esedlar http://www.example.com/
   users/esedlar is granted the DAV:read, DAV:write, and DAV:read-acl
   privileges.

   ACE #2: The principals identified by the URL
         http://www.example.com/groups/marketing http://www.example.com/
   groups/marketing are denied the DAV:read privilege.  In this example,
   the principal URL identifies a group.

   ACE #3: In this ACE, the principal is a property principal,
   specifically the DAV:owner property. When evaluating this ACE, the
   value of the DAV:owner property is retrieved, and is examined to see
   if it contains a DAV:href XML element. If so, the URL within the
   DAV:href element is read, and identifies a principal. In this ACE,
   the owner is granted DAV:read-acl, and DAV:write-acl privileges.

   ACE #4: This ACE grants the DAV:all principal (all users) the
   DAV:read privilege. This ACE is inherited from the resource
         http://www.example.com/top, http://
   www.example.com/top, the parent collection of this resource.

    6

6. ACL EVALUATION Evaluation

   WebDAV ACLs are evaluated in similar manner as ACLs on Windows NT and
   in NFSv4 [NFSV4]). [RFC3530]).  An ACL is evaluated to determine whether or not
   access will be granted for a WebDAV request.  ACEs are maintained in
   a particular order, and are evaluated until all of the permissions
   required by the current request have been granted, at which point the
   ACL evaluation is terminated and access is granted.  If, during ACL
   evaluation, a <deny> ACE (matching the current user) is encountered
   for a privilege which has not yet been granted, the ACL evaluation is
   terminated and access is denied.  Failure to have all required
   privileges granted results in access being denied.

   Note that the semantics of many other existing ACL systems may be
   represented via this mechanism, by mixing deny and grant ACEs. For
   example, consider the standard "rwx" privilege scheme used by UNIX.
   In this scheme, if the current user is the owner of the file, access
   is granted if the corresponding privilege bit is set and denied if
   not set, regardless of the permissions set on the

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 30] 
         fileĂs file's group and
   for the world.  An ACL for UNIX permissions of
         "r--rw-r--"might "r--rw-r--" might be
   constructed like:

   <D:acl>
     <D:ace>
                 <D:principal><D:property>
                   <D:owner/></D:property></D:principal>
                 <D:grant><D:privilege><D:read/></D:privilege></D:grant>
       <D:principal>
         <D:property><D:owner/></D:property>
       </D:principal>
       <D:grant>
         <D:privilege><D:read/></D:privilege>
       </D:grant>
     </D:ace>
     <D:ace>
                 <D:principal><D:property>
                   <D:owner/> </D:property></D:principal>
                 <D:deny><D:privilege><D:all/></D:privilege></D:deny>
       <D:principal>
         <D:property><D:owner/></D:property>
       </D:principal>
       <D:deny>
         <D:privilege><D:all/></D:privilege>
       </D:deny>
     </D:ace>
     <D:ace>
                 <D:principal><D:property>
                   <D:group/> </D:property></D:principal>
                 <D:grant><D:privilege><D:read/></D:privilege>
                   <D:privilege><D:write/></D:privilege></D:grant>
       <D:principal>
         <D:property><D:group/></D:property>
       </D:principal>
       <D:grant>
         <D:privilege><D:read/></D:privilege>
         <D:privilege><D:write/></D:privilege>
       </D:grant>
     </D:ace>
     <D:ace>
                 <D:principal><D:property>
                   <D:group/> </D:property></D:principal>
                 <D:deny><D:privilege><D:all/></D:privilege></D:deny>
       <D:principal>
         <D:property><D:group/></D:property>
       </D:principal>
       <D:deny>
         <D:privilege><D:all/></D:privilege>
       </D:deny>
     </D:ace>
     <D:ace>
       <D:principal><D:all></D:principal>
                 <D:grant><D:privilege><D:read/></D:privilege></D:grant>
       <D:grant>
         <D:privilege><D:read/></D:privilege>
       </D:grant>
     </D:ace>
   </D:acl>

   and the <acl-restrictions> would be defined as:

   <D:no-invert/>
   <D:required-principal>
     <D:all/>
     <D:property><D:owner/></D:property>
     <D:property><D:group/><D:group/>
   </D:required-principal>

   Note that the client can still get errors from a UNIX server in spite
   of obeying the <acl-restrictions>, including <D:allowed-
         principal> <D:allowed-principal>
   (adding an ACE specifying a principal other than the ones in the ACL
   above) or <D:ace-conflict> (by trying to reorder the ACEs in the
   example above), as these particular implementation semantics are too
   complex to be captured with the simple (but general) declarative
   restrictions.

    7  ACCESS CONTROL AND EXISTING METHODS

7. Access Control and existing methods

   This section defines the impact of access control functionality on
   existing methods.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 31]

7.1 ANY Any HTTP METHOD method

7.1.1 Error Handling

   The WebDAV ACL mechanism requires the usage of HTTP method
   "preconditions" as described in section 1.6 of RFC3253 for ALL HTTP
   methods.  All HTTP methods have an additional precondition called
   DAV:need-privileges.  If an HTTP method fails due to insufficient
   privileges, the response body to the "403 Forbidden" error MUST
   contain the <DAV:error> element, which in turn contains the
   <DAV:need-privileges> element, which contains one or more
   <DAV:resource> elements indicating which resource had insufficient
   privileges, and what the lacking privileges were:

   <!ELEMENT need-privileges (resource)* >
   <!ELEMENT resource ( href , privilege ) >

   Since some methods require multiple permissions on multiple
   resources, this information is needed to resolve any ambiguity. There
   is no requirement that all privilege violations be reported¨ reported - for
   implementation reasons, some servers may only report the first
   privilege violation. For example:

   >> Request <<

   MOVE /a/b/ HTTP/1.1
   Host: www.example.com
   Destination: http://www.example.com/c/d

   >> Response <<

   HTTP/1.1 403 Forbidden
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <D:error xmlns:D="DAV:">
     <D:need-privileges>
       <D:resource>
         <D:href>/a</D:href>
         <D:privilege><D:unbind/></D:privilege>
       </D:resource>
       <D:resource>
         <D:href>/c</D:href>
         <D:privilege><D:bind/></D:privilege>
       </D:resource>
     </D:need-privileges>
   </D:error>

7.2 OPTIONS

   If the server supports access control, it MUST return "access-
         control"
   "access-control" as a field in the DAV response header from an
   OPTIONS request on any resource implemented by that server. A value
   of "access-control" in the DAV header MUST indicate that the server

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 32]
   supports all MUST level requirements and REQUIRED features specified
   in this document.

7.2.1 Example - OPTIONS

   >> Request <<

   OPTIONS /foo.html HTTP/1.1
   Host: www.example.com
   Content-Length: 0

   >> Response <<

   HTTP/1.1 200 OK
   DAV: 1, 2, access-control
   Allow: OPTIONS, GET, PUT, PROPFIND, PROPPATCH, ACL
   In this example, the OPTIONS response indicates that the server
   supports access control and that /foo.html can have its access
   control list modified by the ACL method.

7.3 MOVE

   When a resource is moved from one location to another due to a MOVE
   request, the non-inherited and non-protected ACEs in the DAV:acl
   property of the resource MUST NOT be modified, or the MOVE request
   fails. Handling of inherited and protected ACEs is intentionally
   undefined to give server implementations flexibility in how they
   implement ACE inheritance and protection.

7.4 COPY

   The DAV:acl property on the resource at the destination of a COPY
   MUST be the same as if the resource was created by an individual
   resource creation request (e.g. MKCOL, PUT). Clients wishing to
   preserve the DAV:acl property across a copy need to read the DAV:acl
   property prior to the COPY, then perform an ACL operation on the new
   resource at the destination to restore, insofar as this is possible,
   the original access control list.

7.5 LOCK

   A lock on a resource ensures that only the lock owner can modify ACEs
   that are not inherited and not protected  (these are the only ACEs
   that a client can modify with an ACL request). A lock does not
   protect inherited or protected ACEs, since a client cannot modify
   them with an ACL request on that resource.

    8  ACCESS CONTROL METHODS

8. Access Control Methods

8.1 ACL

   The ACL method modifies the access control list (which can be read
   via the DAV:acl property) of a resource.  Specifically, the ACL

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 33]  Specifically, the ACL
   method only permits modification to ACEs that are not inherited, and
   are not protected. An ACL method invocation modifies all non-
         inherited
   non-inherited and non-protected ACEs in a resource's access control
   list to exactly match the ACEs contained within in the DAV:acl XML
   element (specified in Section 5.4) 5.5) of the request body. An ACL
   request body MUST contain only one DAV:acl XML element. Unless the
   non-inherited and non-protected ACEs of the DAV:acl property of the
   resource can be updated to be exactly the value specified in the ACL
   request, the ACL request MUST fail.

   It is possible that the ACEs visible to the current user in the
   DAV:acl property may only be a portion of the complete set of ACEs on
   that resource. If this is the case, an ACL request only modifies the
   set of ACEs visible to the current user, and does not affect any
   non-visible ACE.

   In order to avoid overwriting DAV:acl changes by another client, a
   client SHOULD acquire a WebDAV lock on the resource before retrieving
   the DAV:acl property of a resource that it intends on updating.

      Implementation Note: Two common operations are to add or remove an
      ACE from an existing access control list. To accomplish this, a
      client uses the PROPFIND method to retrieve the value of the
      DAV:acl property, then parses the returned access control list to
      remove all inherited and protected ACEs (these ACEs are tagged
      with the DAV:inherited and DAV:protected XML elements). In the
      remaining set of non-inherited, non-protected ACEs, the client can
      add or remove one or more ACEs before submitting the final ACE set
      in the request body of the ACL method.

8.1.1 ACL Preconditions

   An implementation MUST enforce the following constraints on an ACL
   request.  If the constraint is violated, a 403 (Forbidden) or 409
   (Conflict) response MUST be returned and the indicated XML element
   MUST be returned as a child of a top level DAV:error element in an
   XML response body.

   Though these status elements are generally expressed as empty XML
   elements (and are defined as EMPTY in the DTD), implementations MAY
   return additional descriptive XML elements as children of the status
   element. Clients MUST be able to accept children of these status
   elements. Clients that do not understand the additional XML elements
   should ignore them.

   (DAV:no-ace-conflict): The ACEs submitted in the ACL request MUST NOT
   conflict with each other.  This is a catchall error code indicating
   that an implementation-specific ACL restriction has been violated.

   (DAV:no-protected-ace-conflict): The ACEs submitted in the ACL
   request MUST NOT conflict with the protected ACEs on the resource.
   For example, if the resource has a protected ACE granting DAV:write
   to a given principal, then it would not be consistent if

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 34] the ACL
   request submitted an ACE denying DAV:write to the same principal.

   (DAV:no-inherited-ace-conflict): The ACEs submitted in the ACL
   request MUST NOT conflict with the inherited ACEs on the resource.
   For example, if the resource inherits an ACE from its parent
   collection granting DAV:write to a given principal, then it would not
   be consistent if the ACL request submitted an ACE denying DAV:write
   to the same principal. Note that reporting of this error will be
   implementation-dependent. Implementations MUST either report this
   error or allow the ACE to be set, and then let normal ACE evaluation
   rules determine whether the new ACE has any impact on the privileges
   available to a specific principal.

   (DAV:limited-number-of-aces): The number of ACEs submitted in the ACL
   request MUST NOT exceed the number of ACEs allowed on that resource.
   However, ACL-compliant servers MUST support at least one ACE granting
   privileges to a single principal, and one ACE granting privileges to
   a group.

   (DAV:deny-before-grant): All non-inherited deny ACEs MUST precede all
   non-inherited grant ACEs.

   (DAV:grant-only): The ACEs submitted in the ACL request MUST NOT
   include a deny ACE.  This precondition applies only when the ACL
   restrictions of the resource include the DAV:grant-only constraint
   (defined in Section 5.5.1). 5.6.1).

   (DAV:no-invert):  The ACL request MUST NOT include a DAV:invert
   element.   This precondition applies only when the ACL semantics of
   the resource includes the DAV:no-invert constraint (defined in
   Section 6.3.4). 5.6.2).

   (DAV:no-abstract): The ACL request MUST NOT attempt to grant or deny
   an abstract privilege (see Section 5.2). 5.3).

   (DAV:not-supported-privilege): The ACEs submitted in the ACL request
   MUST be supported by the resource.

   (DAV:missing-required-principal): The result of the ACL request MUST
   have at least one ACE for each principal identified in a
   DAV:required-principal XML element in the ACL semantics of that
   resource (see Section 5.5.4). 5.5).

   (DAV:recognized-principal): Every principal URL in the ACL request
   MUST identify a principal resource.

   (DAV:allowed-principal): The principals specified in the ACEs
   submitted in the ACL request MUST be allowed as principals for the
   resource. For example, a server where only authenticated principals
   can access resources would not allow the DAV:all or
   DAV:unauthenticated principals to be used in an ACE, since these
   would allow unauthenticated access to resources.

8.1.2 Example: the the ACL method

   In the following example, user "fielding", authenticated by
   information in the Authorization header, grants the principal
   identified by the URL http://www.example.com/users/esedlar  (i.e.,
   the user "esedlar") read and write privileges, grants the owner of
   the resource read-acl and write-acl privileges, and grants everyone
   read privileges.

   >> Request <<

   ACL /top/container/ HTTP/1.1
   Host: www.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx
   Authorization: Digest username="fielding",
     realm="users@example.com", nonce="...",
     uri="/top/container/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:acl xmlns:D="DAV:">
     <D:ace>
       <D:principal>
         <D:href>http://www.example.com/users/esedlar</D:href>
       </D:principal>
       <D:grant>
         <D:privilege><D:read/></D:privilege>
         <D:privilege><D:write/></D:privilege>
       </D:grant>
     </D:ace>
     <D:ace>
       <D:principal>
         <D:property><D:owner/></D:property>
       </D:principal>
       <D:grant>
         <D:privilege><D:read-acl/></D:privilege>
         <D:privilege><D:write-acl/></D:privilege>
       </D:grant>
     </D:ace>
     <D:ace>
       <D:principal><D:all/></D:principal>
       <D:grant>
         <D:privilege><D:read/></D:privilege>
       </D:grant>
     </D:ace>
   </D:acl>
   >> Response <<

   HTTP/1.1 200 OK

8.1.3 Example: ACL method failure due to protected ACE conflict

   In the following request, user "fielding", authenticated by
   information in the Authorization header, attempts to deny the
   principal identified by the URL http://www.example.com/users/esedlar
   (i.e., the user "esedlar") write privileges. Prior to the request,
   the DAV:acl property on the resource contained a protected ACE (see
   Section 5.5.3) granting DAV:owner the DAV:read and DAV:write
   privileges. The principal identified by URL http://www.example.com/
   users/esedlar is the owner of the resource. The ACL method invocation
   fails because the submitted ACE conflicts with the protected ACE,
   thus violating the semantics of ACE protection.

   >> Request <<

   ACL /top/container/ HTTP/1.1
   Host: www.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx
   Authorization: Digest username="fielding",
     realm="users@example.com", nonce="...",
     uri="/top/container/", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:acl xmlns:D="DAV:">
     <D:ace>
       <D:principal>
         <D:href>http://www.example.com/users/esedlar</D:href>
       </D:principal>
       <D:deny>
         <D:privilege><D:write/></D:privilege>
       </D:deny>
     </D:ace>
   </D:acl>
   >> Response <<

   HTTP/1.1 403 Forbidden
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:error xmlns:D="DAV:">
     <D:no-protected-ace-conflict/>
   </D:error>

8.1.4 Example: ACL method failure due to an inherited ACE conflict

   In the following example, request, user "fielding", "ejw", authenticated by information in
   the Authorization header, tries to change the access control list on
   the resource http://www.example.com/top/index.html. This resource has
   two inherited ACEs.

   Inherited ACE #1 grants the principal identified by the URL http://www.example.com/users/esedlar http://
   www.example.com/users/ejw (i.e.,

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 35] the user "esedlar") read "ejw") http://
   www.example.com/privs/write-all and write privileges, DAV:read-acl privileges. On this
   server, http://www.example.com/privs/write-all is an aggregate
   privilege containing DAV:write, and DAV:write-acl.

   Inherited ACE #2 grants principal DAV:all the owner of DAV:read privilege.

   The request attempts to set a (non-inherited) ACE, denying the resource read-acl and write-acl privileges,
   principal identified by the URL http://www.example.com/users/ejw
   (i.e., the user "ejw") DAV:write permission. This conflicts with
   inherited ACE #1. Note that the decision to report an inherited ACE
   conflict is specific to this server implementation. Another server
   implementation could have allowed the new ACE to be set, and grants
         everyone read privileges. then
   used normal ACE evaluation rules to determine whether the new ACE has
   any impact on the privileges available to a principal.

   >> Request <<

   ACL /top/container/ /top/index.html HTTP/1.1
   Host: www.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx
   Authorization: Digest username="fielding",
            realm="users@foo.org", username="ejw",
     realm="users@example.com", nonce="...",
            uri="/top/container/",
     uri="/top/index.html", response="...", opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:acl xmlns:D="DAV:">
           <D:ace>
             <D:principal>
               <D:href>http://www.example.com/users/esedlar</D:href>
             </D:principal>
             <D:grant>
               <D:privilege> <D:read/> </D:privilege>
               <D:privilege> <D:write/> </D:privilege>
             </D:grant>
           </D:ace>
           <D:ace>
             <D:principal>
               <D:property> <D:owner/> </D:property>
             </D:principal>
             <D:grant>
               <D:privilege> <D:read-acl/> </D:privilege>
               <D:privilege> <D:write-acl/> </D:privilege>
             </D:grant>
           </D:ace> xmlns:D="DAV:" xmlns:F="http://www.example.com/privs/">
     <D:ace>
       <D:principal> <D:all/>
          <D:href>http://www.example.com/users/ejw</D:href>
       </D:principal>
             <D:grant>
               <D:privilege> <D:read/> </D:privilege>
             </D:grant>
       <D:grant><D:write/></D:grant>
     </D:ace>
   </D:acl>

   >> Response <<

   HTTP/1.1 200 OK

    8.1.3 403 Forbidden
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:error xmlns:D="DAV:">
     <D:no-inherited-ace-conflict/>
   </D:error>

8.1.5 Example: ACL method failure due to protected ACE conflict

         In an attempt to set grant and
      deny in a single ACE

   In this example, user "ygoland", authenticated by information in the
   Authorization header, tries to change the access control list on the
   resource http://www.example.com/diamond/engagement-ring.gif. The ACL
   request includes a single, syntactically and semantically incorrect
   ACE, which attempts to grant the following request, user "fielding", authenticated group identified by
         information in the Authorization header, attempts to URL http://
   www.example.com/users/friends DAV:read privilege and deny the
   principal identified by the URL
         http://www.example.com/users/esedlar http://www.example.com/users/ygoland-so
   (i.e., the user "esedlar")
         write privileges. Prior "ygoland-so") DAV:read privilege. However, it is
   illegal to the request, the DAV:acl property on
         the resource contained have multiple principal elements, as well as both a protected ACE (see Section 5.4.3)
         granting DAV:owner the DAV:read grant
   and DAV:write privileges. The

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 36] 
         principal identified by URL http://www.example.com/users/esedlar
         is the owner of the resource. The ACL method invocation fails
         because the submitted ACE conflicts with deny element in the protected same ACE, thus
         violating so the semantics of ACE protection. request fails due to poor
   syntax.

   >> Request <<

   ACL /top/container/ /diamond/engagement-ring.gif HTTP/1.1
   Host: www.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx
   Authorization: Digest username="fielding",
            realm="users@foo.org", username="ygoland",
     realm="users@example.com", nonce="...",
            uri="/top/container/",
     uri="/diamond/engagement-ring.gif", response="...",
     opaque="..."

   <?xml version="1.0" encoding="utf-8" ?>
   <D:acl xmlns:D="DAV:">
     <D:ace>
       <D:principal>
               <D:href>http://www.example.com/users/esedlar</D:href>
         <D:href>http://www.example.com/users/friends</D:href>
       </D:principal>
             <D:deny>
               <D:privilege> <D:write/> </D:privilege>
             </D:deny>
       <D:grant><D:read/></D:grant>
       <D:principal>
         <D:href>http://www.example.com/users/ygoland-so</D:href>
       </D:principal>
       <D:deny><D:read/></D:deny>
     </D:ace>
   </D:acl>

   >> Response <<

   HTTP/1.1 403 Forbidden
         Content-Type: text/xml; charset="utf-8" 400 Bad Request
   Content-Length: xxx

         <?xml version="1.0" encoding="utf-8" ?>
         <D:error xmlns:D="DAV:">
           <D:no-protected-ace-conflict/>
         </D:error>

    8.1.4 Example: ACL 0

   Note that if the request had been divided into two ACEs, one to
   grant, and one to deny, the request would have been syntactically
   well formed.

9. Access Control Reports

9.1 REPORT Method

   The REPORT method failure due (defined in Section 3.6 of [RFC3253]) provides an
   extensible mechanism for obtaining information about a resource.
   Unlike the PROPFIND method, which returns the value of one or more
   named properties, the REPORT method can involve more complex
   processing. REPORT is valuable in cases where the server has access
   to all of the information needed to perform the complex request (such
   as a query), and where it would require multiple requests for the
   client to an inherited ACE conflict

         In retrieve the following request, user "ejw", authenticated by information
         in the Authorization header, tries needed to change perform the access control
         list on same
   request.

   A server that supports the resource http://www.example.com/top/index.html. This
         resource has two inherited ACEs.
         Inherited ACE #1 grants WebDAV Access Control Protocol MUST
   support the principal DAV:expand-property report (defined in Section 3.8 of
   [RFC3253]).

9.2 DAV:acl-principal-prop-set Report

   The DAV:acl-principal-prop-set report returns, for all principals in
   the DAV:acl property (of the Request-URI) that are identified by URL
         http://www.example.com/users/ejw (i.e.,
   http(s) URLs or by a DAV:property principal, the user "ejw")
         http://www.example.com/privs/write-all and DAV:read-acl
         privileges. On this server, http://www.example.com/privs/write-all
         is an aggregate privilege containing DAV:write, and DAV:write-acl.
         Inherited ACE #2 grants principal DAV:all value of the DAV:read privilege.
         The
   properties specified in the REPORT request attempts to set body. In the case where a (non-inherited) ACE, denying
   principal URL appears multiple times, the DAV:acl-principal-prop-set
   report MUST return the properties for that principal identified by only once.
   Support for this report is REQUIRED.

   One expected use of this report is to retrieve the URL http://www.example.com/users/ejw
         (i.e., human readable
   name (found in the user "ejw") DAV:write permission. DAV:displayname property) of each principal found
   in an ACL. This conflicts with

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 37] 
         inherited is useful for constructing user interfaces that show
   each ACE #1. in a human readable form.

   Marshalling

      The request body MUST be a DAV:acl-principal-prop-set XML element.

      <!ELEMENT acl-principal-prop-set ANY>
      ANY value: a sequence of one or more elements, with at most one
                 DAV:prop element.
      prop: see RFC 2518, Section 12.11

      This report is only defined when the Depth header has value "0";
      other values result in a 400 (Bad Request) error response. Note
      that [RFC3253], Section 3.6, states that if the decision to report an inherited
         ACE conflict Depth header is specific to this server implementation. Another
         server implementation could have allowed the new ACE
      not present, it defaults to a value of "0".

      The response body for a successful request MUST be set,
         and then used normal ACE evaluation rules to determine whether a
      DAV:multistatus XML element (i.e., the
         new ACE has any impact on response uses the privileges available to a principal.
         >> Request <<

         ACL /top/index.html HTTP/1.1
         Host: www.example.com
         Content-Type: text/xml; charset="utf-8"
         Content-Length: xxxx
         Authorization: Digest username="ejw",
            realm="users@foo.org", nonce="...",
            uri="/top/index.html", response="...", opaque="..."

         <?xml version="1.0" encoding="utf-8" ?>
         <D:acl xmlns:D="DAV:" xmlns:F="http://www.example.com/privs/">
           <D:ace>
               <D:principal>
                 <D:href>http://www.example.com/users/ejw</D:href>
               </D:principal>
               <D:grant><D:write/></D:grant>
           </D:ace>
         </D:acl>

         >> Response <<

         HTTP/1.1 403 Forbidden
         Content-Type: text/xml; charset="utf-8"
         Content-Length: xxx

         <?xml version="1.0" encoding="utf-8" ?>
         <D:error xmlns:D="DAV:">
           <D:no-inherited-ace-conflict xmlns:D="DAV:"/>
         </D:error>

    8.1.5 Example: ACL method failure due to an attempt to set grant and
         deny in a single ACE.

         In this example, user "ygoland", authenticated by information in same
      format as the Authorization header, tries to change response for PROPFIND). In the access control list
         on case where there are
      no response elements, the resource http://www.example.com/diamond/engagement-
         ring.gif. returned multistatus XML element is
      empty.

      multistatus: see RFC 2518, Section 12.9

      The ACL response body for a successful DAV:acl-principal-prop-set
      REPORT request includes MUST contain a single, syntactically and
         semantically incorrect ACE, which attempts to grant DAV:response element for each
      principal identified by an http(s) URL listed in a DAV:principal
      XML element of an ACE within the group DAV:acl property of the resource
      identified by the URL http://www.example.com/users/friends Request-URI.

   Postconditions:

      (DAV:number-of-matches-within-limits): The number of matching
      principals must fall within server-specific, predefined limits.
      For example, this condition might be triggered if a search
      specification would cause the return of an extremely large number
      of responses.

9.2.1 Example: DAV:acl-principal-prop-set Report

   Resource http://www.example.com/index.html has an ACL with three
   ACEs:

   ACE #1: All principals (DAV:all) have DAV:read privilege and deny the
   DAV:read-current-user-privilege-set access.

   ACE #2: The principal identified by URL
         http://www.example.com/users/ygoland-so (i.e., the http://www.example.com/people/
   gstein (the user "ygoland-
         so") DAV:read privilege. However, it "gstein") is illegal to have multiple
         principal elements, as well as both a grant granted DAV:write,  DAV:write-acl,
   DAV:read-acl privileges.

   ACE #3: The group identified by http://www.example.com/groups/authors
   (the "authors" group) is granted DAV:write and deny element in DAV:read-acl
   privileges.

   The following example shows a DAV:acl-principal-prop-set report
   requesting the same ACE, so DAV:displayname property. It returns the request fails due to poor syntax. value of
   DAV:displayname for resources http://www.example.com/people/gstein
   and http://www.example.com/groups/authors , but not for DAV:all,
   since this is not an http(s) URL.

   >> Request <<

         ACL /diamond/engagement-ring.gif

   REPORT /index.html HTTP/1.1

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 38]
   Host: www.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx
         Authorization: Digest username="ygoland",
            realm="users@foo.org", nonce="...",
            uri="/diamond/engagement-ring.gif", response="...",
         opaque="..."
   Depth: 0

   <?xml version="1.0" encoding="utf-8" ?>
         <D:acl
   <D:acl-principal-prop-set xmlns:D="DAV:">
             <D:ace>
               <D:principal>
                 <D:href>http://www.example.com/users/friends</D:href>
               </D:principal>
               <D:grant><D:read/></D:grant>
               <D:principal>
                 <D:href>http://www.example.com/users/ygoland-so</D:href>
               </D:principal>
               <D:deny><D:read/></D:deny>
             </D:ace>
         </D:acl>
     <D:prop>
       <D:displayname/>
     </D:prop>
   </D:acl-principal-prop-set>
   >> Response <<

   HTTP/1.1 400 Bad Request 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: 0

         Note that if the request had been divided into two ACEs, one to
         grant, and one to deny, the request would have been syntactically
         well formed.

    9  ACCESS CONTROL REPORTS

    9.1 REPORT Method

         The REPORT method (defined in Section 3.6 of [RFC3253]) provides
         an extensible mechanism for obtaining information about a
         resource.  Unlike the PROPFIND method, which returns the value of
         one or more named properties, the xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.com/people/gstein</D:href>
       <D:propstat>
         <D:prop>
           <D:displayname>Greg Stein</D:displayname>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>http://www.example.com/groups/authors</D:href>
       <D:propstat>
         <D:prop>
           <D:displayname>Site authors</D:displayname>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

9.3 DAV:principal-match REPORT method can involve more
         complex processing.

   The DAV:principal-match REPORT is valuable in cases where the server
         has access used to identify all members (at
   any depth) of the information needed to perform collection identified by the complex
         request (such as a query), Request-URI that are
   principals and where it would require multiple
         requests for that match the client to retrieve current user. In particular, if the information needed
   collection contains principals, the report can be used to
         perform identify
   all members of the same request.
         A server collection that supports the WebDAV Access Control Protocol MUST
         support match the DAV:expand-property report (defined in Section 3.8 of
         [RFC3253]).

    9.2 DAV:acl-principal-prop-set Report

         The DAV:acl-principal-prop-set report returns, for all principals
         in current user.
   Alternatively, if the DAV:acl collection contains resources that have a
   property (of the Request-URI) that are identified
         by http(s) URLs or by identifies a DAV:property principal, principal (e.g. DAV:owner), the value report can
   be used to identify all members of the

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 39] 
         properties specified in the REPORT request body. In the case where collection whose property
   identifies a principal URL appears multiple times, that matches the DAV:acl-principal-
         prop-set current user. For example,
   this report MUST can return all of the properties for resources in a collection hierarchy
   that principal only
         once. are owned by the current user. Support for this report is
   REQUIRED.
         One expected use of this report is to retrieve the human readable
         name (found in the DAV:displayname property) of each principal
         found in an ACL. This is useful for constructing user interfaces
         that show each ACE in a human readable form.
       Marshalling

   Marshalling:

      The request body MUST be a DAV:acl-principal-prop-set DAV:principal-match XML element.

      <!ELEMENT acl-principal-prop-set principal-match ((principal-property | self), prop?)>
      <!ELEMENT principal-property ANY>
      ANY value: an element whose value identifies a sequence property. The
      expectation is the value of one or more elements, with at most one
         DAV:prop element. the named property typically contains
      an href element that contains the URI of a principal
      <!ELEMENT self EMPTY>
      prop: see RFC 2518, Section 12.11

      This report is only defined when the Depth header has value "0";
      other values result in a 400 (Bad Request) error response. Note
      that [RFC3253], Section 3.6, states that if the Depth header is
      not present, it defaults to a value of "0". The response body for
      a successful request MUST be a DAV:multistatus XML element (i.e., the response uses the same
         format as the response for PROPFIND). element. In the
      case where there are no response elements, the returned
      multistatus XML element is empty.

      multistatus: see RFC 2518, Section 12.9

      The response body for a successful DAV:acl-principal-prop-set DAV:principal-match REPORT
      request MUST contain a DAV:response element for each member of the
      collection that matches the current user. When the
      DAV:principal-property element is used, a match occurs if the
      current user is matched by the principal identified by an http(s) URL listed the URI
      found in a DAV:principal
         XML the DAV:href element of an ACE within the DAV:acl property of the resource identified by the Request-URI.
       Postconditions:
         (DAV:number-of-matches-within-limits): The number of matching
         principals must fall within server-specific, predefined limits.
         For example, this condition might be triggered
      DAV:principal-property element. When the DAV:self element is used
      in a DAV:principal-match report issued against a group, it matches
      the group if a search
         specification would cause member identifies the return of an extremely large number
         of responses.

    9.2.1 Example: DAV:acl-principal-prop-set Report

         Resource http://www.example.com/index.html has an ACL with three
         ACEs:
         ACE #1: All principals (DAV:all) have DAV:read and DAV:read-
         current-user-privilege-set access.
         ACE #2: The same principal identified by
         http://www.example.com/people/gstein (the user "gstein") is
         granted DAV:write,  DAV:write-acl, DAV:read-acl privileges.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 40] 
         ACE #3: The group identified by
         http://www.example.com/groups/authors (the "authors" group) as the current
      user.

      If DAV:prop is
         granted DAV:write and DAV:read-acl privileges.
         The following example shows a DAV:acl-principal-prop-set report
         requesting specified in the DAV:displayname property. It returns request body, the properties
      specified in the DAV:prop element MUST be reported in the
      DAV:response elements.

9.3.1 Example: DAV:principal-match REPORT

   The following example identifies the value members of
         DAV:displayname for resources http://www.example.com/people/gstein
         and http://www.example.com/groups/authors , but not for DAV:all,
         since this the collection
   identified by the URL http://www.example.com/doc that are owned by
   the current user. The current user ("gclemm") is not an http(s) URL. authenticated using
   Digest authentication.

   >> Request <<

   REPORT /index.html /doc/ HTTP/1.1
   Host: www.example.com
   Authorization: Digest username="gclemm",
     realm="users@example.com", nonce="...",
     uri="/papers/", response="...", opaque="..."
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx
   Depth: 0

   <?xml version="1.0" encoding="utf-8" ?>
         <D:acl-principal-prop-set
   <D:principal-match xmlns:D="DAV:">
           <D:prop>
             <D:displayname/>
           </D:prop>
         </D:acl-principal-prop-set>
     <D:principal-property>
       <D:owner/>
     </D:principal-property>
   </D:principal-match>

   >> Response <<

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
             <D:href>http://www.example.com/people/gstein</D:href>
             <D:propstat>
               <D:prop>
                 <D:displayname>Greg Stein</D:displayname>
               </D:prop>
       <D:href>http://www.example.com/doc/foo.html</D:href>
       <D:status>HTTP/1.1 200 OK</D:status>
             </D:propstat>
     </D:response>
     <D:response>
             <D:href>http://www.example.com/groups/authors</D:href>
             <D:propstat>
               <D:prop>
                 <D:displayname>Site authors</D:displayname>
               </D:prop>
       <D:href>http://www.example.com/doc/img/bar.gif</D:href>
       <D:status>HTTP/1.1 200 OK</D:status>
             </D:propstat>
     </D:response>
   </D:multistatus>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 41] 
    9.3 DAV:principal-match

9.4 DAV:principal-property-search REPORT

   The DAV:principal-match DAV:principal-property-search REPORT is used to identify performs a search for all members (at
         any depth) of the collection identified by the Request-URI that
         are
   principals and whose properties contain character data that match the current user. In particular, if matches the collection contains principals,
   search criteria specified in the request. One expected use of this
   report can be used is to
         identify all members of the collection that match the current
         user. Alternatively, if discover the collection contains resources that
         have a property that identifies URL of a principal (e.g. DAV:owner), associated with a given
   person or group by searching for them by name. This is done by
   searching over DAV:displayname, which is defined on all principals.

   The actual search method (exact matching vs. substring matching vs,
   prefix-matching, case-sensitivity) deliberately is left to the
         report can be used server
   implementation to identify all members allow implementation on a wide set of possible user
   management systems. In cases where the collection whose
         property identifies a principal that matches implementation of
   DAV:principal-property-search is not constrained by the current user. semantics of
   an underlying user management repository, preferred default semantics
   are caseless substring matches.

   For
         example, this report can return implementation efficiency, servers do not typically support
   searching on all of the resources in a
         collection hierarchy properties. A search requesting properties that are owned by the current user.
   not searchable for a particular principal will not match that
   principal.

   Support for this the DAV:principal-property-search report is REQUIRED.
       Marshalling:

      Implementation Note: The request body MUST be a DAV:principal-match XML element.
         <!ELEMENT principal-match ((principal-property | self), prop?)>
         <!ELEMENT principal-property ANY>
         ANY value: an element whose value identifies of a property. The
         expectation WebDAV property is the value a sequence
      of well-formed XML, and hence can include any character in the named property typically contains
         an href element
      Unicode/ISO-10646 standard, that contains the URI of a principal
         <!ELEMENT self EMPTY>
         prop: see RFC 2518, Section 12.11

         This report is only defined when the Depth header has value "0";
         other values result is, most known characters in a 400 (Bad Request) error response. Note
         that [RFC3253], Section 3.6, states that if the Depth header is
         not present, it defaults
      human languages. Due to a value of "0".
         The response body for a successful request MUST be a
         DAV:multistatus XML element. In the idiosyncrasies of case where there are no
         response elements, the returned multistatus XML element mapping across
      human languages, implementation of case-insensitive matching is empty.
         multistatus: see RFC 2518,
      non-trivial. Implementors of servers that do perform substring
      matching are strongly encouraged to consult "The Unicode Standard"
      [UNICODE4], especially Section 12.9

         The response body 5.18, Subsection "Caseless
      Matching", for a successful DAV:principal-match REPORT
         request MUST contain a DAV:response element guidance when implementing their case-insensitive
      matching algorithms.

      Implementation Note: Some implementations of this protocol will
      use an LDAP repository for each member storage of the
         collection that matches the current user. When the DAV:principal-
         property element is used, a match occurs if the current user is
         matched by the principal identified by the URI found metadata. The
      schema describing each attribute (akin to a WebDAV property) in the
         DAV:href element an
      LDAP repository specifies whether it supports case-sensitive or
      caseless searching. One of the property identified by the DAV:principal-
         property element. When the DAV:self element is used in a
         DAV:principal-match report issued against a group, it matches benefits of leaving the
         group if a member identifies search
      method to the same principal as discretion of the current
         user.
         If DAV:prop server implementation is specified in the request body, the properties
         specified in the DAV:prop element MUST
      default LDAP attribute search behavior can be reported in the
         DAV:response elements.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 42] 
    9.3.1 Example: DAV:principal-match REPORT

         The following example identifies the members of the collection
         identified by the URL http://www.example.com/doc that are owned by used when
      implementing the current user. The current user ("gclemm") is authenticated
         using Digest authentication.
         >> Request <<
         REPORT /doc/ HTTP/1.1
         Host: www.example.com
         Authorization: Digest username="gclemm",
            realm="gclemm@webdav.org", nonce="...",
            uri="/papers/", response="...", opaque="..."
         Content-Type: text/xml; charset="utf-8"
         Content-Length: xxxx
         Depth: 0

         <?xml version="1.0" encoding="utf-8" ?>
         <D:principal-match xmlns:D="DAV:">
           <D:principal-property>
             <D:owner/>
           </D:principal-property>
         </D:principal-match>

         >> Response <<

         HTTP/1.1 207 Multi-Status
         Content-Type: text/xml; charset="utf-8"
         Content-Length: xxxx

         <?xml version="1.0" encoding="utf-8" ?>
         <D:multistatus xmlns:D="DAV:">
           <D:response>
             <D:href>http://www.example.com/doc/foo.html</D:href>
             <D:status>HTTP/1.1 200 OK</D:status>
           </D:response>
           <D:response>
             <D:href>http://www.example.com/doc/img/bar.gif</D:href>
             <D:status>HTTP/1.1 200 OK</D:status>
           </D:response>
         </D:multistatus>

    9.4 DAV:principal-property-search REPORT report.

   Marshalling:

      The DAV:principal-property-search REPORT performs request body MUST be a search for all
         principals whose properties contain character data DAV:principal-property-search XML
      element containing a search specification and an optional list of
      properties. For every principal that matches the search criteria specified in
      specification, the request. One expected use response will contain the value of
         this report is to discover the URL
      requested properties on that principal.

      <!ELEMENT principal-property-search
       ((property-search+), prop?, apply-to-principal-collection-set?) >

      By default, the report searches all members (at any depth) of a principal associated with
         a given person or group by searching for them by name. This is
         done the
      collection identified by searching over DAV:displayname, which the Request-URI.  If
      DAV:apply-to-principal-collection-set is defined on all
         principals.
         The actual search method (exact matching vs. substring matching
         vs, prefix-matching, case-sensitivity) deliberately specified in the request
      body, the request is left applied instead to each collection identified
      by the

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 43] 
         server implementation to allow implementation on a wide set DAV:prinicipal-collection-set property of
         possible user management systems. In cases where the
         implementation of DAV:principal-property-search is not constrained resource
      identified by the semantics of an underlying user management repository,
         preferred default semantics are caseless substring matches.
         For implementation efficiency, servers do not typically support
         searching on all properties. A search requesting Request-URI.

      The DAV:property-search element contains a prop element
      enumerating the properties that
         are not searchable for to be searched and a particular principal will not match element,
      containing the search string.

      <!ELEMENT property-search (prop, match) >
      prop: see RFC 2518, Section 12.11

      <!ELEMENT match #PCDATA >

      Multiple property-search elements or multiple elements within a
      DAV:prop element will be interpreted with a logical AND.

      This report is only defined when the Depth header has value "0";
      other values result in a 400 (Bad Request) error response. Note
      that [RFC3253], Section 3.6, states that
         principal.
         Support for if the DAV:principal-property-search report Depth header is REQUIRED.
           Implementation Note: The
      not present, it defaults to a value of "0".

      The response body for a WebDAV property is successful request MUST be a
           sequence of well-formed XML, and hence can include any
           character in the Unicode/ISO-10646 standard, that is, most
           known characters in human languages. Due to
      DAV:multistatus XML element. In the idiosyncrasies
           of case mapping across human languages, implementation of case-
           insensitive matching is non-trivial. Implementors of servers
           that do perform substring matching where there are strongly encouraged to
           consult [CaseMap], especially no
      response elements, the returned multistatus XML element is empty.

      multistatus: see RFC 2518, Section 2.3 ("Caseless
           Matching"), 12.9

      The response body for guidance when implementing their case-
           insensitive matching algorithms.
           Implementation Note: Some implementations of this protocol will
           use an LDAP repository a successful DAV:principal-property-search
      REPORT request MUST contain  a DAV:response element for storage of principal metadata. The
           schema describing each attribute (akin to a WebDAV property)
      principal whose property values satisfy the search specification
      given in DAV:principal-property-search.

      The response body for an LDAP repository specifies whether it supports case-sensitive unsuccessful
      DAV:principal-property-search REPORT request MUST contain, after
      the XML element indicating the failed precondition or caseless searching. One
      postcondition, a DAV:prop element containing the property that
      caused the pre/postcondition to fail.

      If DAV:prop is specified in the request body, the properties
      specified in the DAV:prop element MUST be reported in the
      DAV:response elements.

   Preconditions:

      None

   Postconditions:

      (DAV:number-of-matches-within-limits): The number of matching
      principals must fall within server-specific, predefined limits.
      For example, this condition might be triggered if a search
      specification would cause the benefits return of an extremely large number
      of leaving responses.

9.4.1 Matching

   There are several cases to consider when matching strings. The
   easiest case is when a property value is "simple" and has only
   character information item content (see [REC-XML-INFOSET]). For
   example, the search method to string "julian" would match the discretion DAV:displayname
   property with value "Julian Reschke". Note that the on-the-wire
   marshalling of DAV:displayname in this case is:

   <D:displayname xmlns:D="DAV:">Julian Reschke</D:displayname>

   The name of the server implementation property is encoded into the default LDAP attribute search behavior can be used when
           implementing the DAV:principal-property-search report.
       Marshalling:
         The request body MUST be a DAV:principal-property-search XML element containing a search specification information
   item, and an optional list of
         properties. For every principal that matches the search
         specification, the response will contain the value character information item content of the
         requested property is
   "Julian Reschke".

   A more complicated case occurs when properties on that principal.
         <!ELEMENT principal-property-search
          ((property-search+), prop?, apply-to-principal-collection-set?) >

         By default, the report searches all members (at any depth) have mixed content
   (that is, compound values consisting of multiple child element items,
   other types of information items, and character information item
   content). Consider the
         collection identified by property "aprop" in the Request-URI.  If DAV:apply-to-
         principal-collection-set namespace "http://
   www.example.com/props/", marshalled as:

   <W:aprop xmlns:W="http://www.example.com/props/">
     {cdata 0}<W:elem1>{cdata 1}</W:elem1>
     <W:elem2>{cdata 2}</W:elem2>{cdata 3}
   </W:aprop>

   In this case, matching is specified in performed on each individual contiguous
   sequence of character information items. In the request body, example above, a
   search string would be compared to the four following strings:

   {cdata 0}
   {cdata 1}
   {cdata 2}
   {cdata 3}

   That is, four individual matches would be performed, one each for
   {cdata 0}, {cdata 1}, {cdata 2}, and {cdata 3}.

9.4.2 Example: successful DAV:principal-property-search REPORT

   In this example, the
         request is applied instead to each collection identified by client requests the
         DAV:prinicipal-collection-set property principal URLs of all users
   whose DAV:displayname property contains the resource identified
         by substring "doE" and whose
   "title" property in the Request-URI.
         The DAV:property-search element namespace "http://BigCorp.com/ns/" (that is,
   their professional title) contains a prop element
         enumerating "Sales".  In addition, the client
   requests five properties to be searched and a match element,
         containing returned with the matching principals:

   In the DAV: namespace: displayname

   In the http://www.example.com/ns/ namespace: department, phone,
   office, salary

   The response shows that two principal resources meet the search string.
         <!ELEMENT property-search (prop, match) >
         prop: see RFC 2518, Section 12.11

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 44] 
         <!ELEMENT match #PCDATA >

         Multiple property-search elements or multiple elements within a
         DAV:prop element will
   specification, "John Doe" and "Zygdoebert Smith". The property
   "salary" in namespace "http://www.example.com/ns/" is not returned,
   since the principal making the request does not have sufficient
   access permissions to read this property.

   >> Request <<

   REPORT /users/ HTTP/1.1
   Host: www.example.com
   Content-Type: text/xml; charset=utf-8
   Content-Length: xxxx
   Depth: 0

   <?xml version="1.0" encoding="utf-8" ?>
   <D:principal-property-search xmlns:D="DAV:">
     <D:property-search>
       <D:prop>
         <D:displayname/>
       </D:prop>
       <D:match>doE</D:match>
     </D:property-search>
     <D:property-search>
       <D:prop xmlns:B="http://www.example.com/ns/">
         <B:title/>
       </D:prop>
       <D:match>Sales</D:match>
     </D:property-search>
     <D:prop xmlns:B="http://www.example.com/ns/">
       <D:displayname/>
       <B:department/>
       <B:phone/>
       <B:office/>
       <B:salary/>
     </D:prop>
   </D:principal-property-search>

   >> Response <<
   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset=utf-8
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:" xmlns:B="http://BigCorp.com/ns/">
     <D:response>
       <D:href>http://www.example.com/users/jdoe</D:href>
       <D:propstat>
         <D:prop>
           <D:displayname>John Doe</D:displayname>
           <B:department>Widget Sales</B:department>
           <B:phone>234-4567</B:phone>
           <B:office>209</B:office>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
       <D:propstat>
         <D:prop>
           <B:salary/>
         </D:prop>
         <D:status>HTTP/1.1 403 Forbidden</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>http://www.example.com/users/zsmith</D:href>
       <D:propstat>
         <D:prop>
           <D:displayname>Zygdoebert Smith</D:displayname>
           <B:department>Gadget Sales</B:department>
           <B:phone>234-7654</B:phone>
           <B:office>114</B:office>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
       <D:propstat>
         <D:prop>
           <B:salary/>
         </D:prop>
         <D:status>HTTP/1.1 403 Forbidden</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>

9.5 DAV:principal-search-property-set REPORT

   The DAV:principal-search-property-set REPORT identifies those
   properties that may be interpreted with a logical AND.
         This report is only defined when searched using the Depth header has value "0";
         other values result
   DAV:principal-property-search REPORT (defined in a 400 (Bad Request) error response. Note
         that [RFC3253], Section 3.6, states that if 9.4).

   Servers MUST support the DAV:principal-search-property-set REPORT on
   all collections identified in the Depth header is
         not present, it defaults to a value of "0".
         The response body for a successful request MUST be a
         DAV:multistatus XML element. In
   DAV:principal-collection-set property.

   An access control protocol user agent could use the case where there are no
         response elements, results of the returned multistatus XML element is empty.
         multistatus: see RFC 2518, Section 12.9

         The response body for a successful DAV:principal-property-search
   DAV:principal-search-property-set REPORT request MUST contain to present a DAV:response element for each
         principal whose property values satisfy query interface
   to the search specification
         given in DAV:principal-property-search.
         The response body user for retrieving principals.

   Support for this report is REQUIRED.

      Implementation Note: Some clients will have only limited screen
      real estate for an unsuccessful DAV:principal-property-
         search REPORT request MUST contain, after the XML element
         indicating the failed precondition or postcondition, display of lists of searchable properties. In
      this case, a DAV:prop
         element containing the property that caused user might appreciate having the pre/postcondition most frequently
      searched properties be displayed on-screen, rather than having to fail.
         If DAV:prop
      scroll through a long list of searchable properties. One mechanism
      for signaling the most frequently searched properties is specified in to return
      them towards the request body, start of a list of properties. A client can then
      preferentially display the list of properties
         specified in order, increasing
      the DAV:prop element MUST be reported in likelihood that the
         DAV:response elements.
       Preconditions:
         None
       Postconditions:
         (DAV:number-of-matches-within-limits): most frequently searched properties will
      appear on-screen, and will not require scrolling for their
      selection.

   Marshalling:

      The number of matching
         principals must fall within server-specific, predefined limits.
         For example, this condition might request body MUST be triggered if a search
         specification would cause the return of an extremely large number
         of responses.

    9.4.1 Matching

         There are several cases to consider when matching strings. The
         easiest case is when a property value empty
      DAV:principal-search-property-set XML element.

      This report is "simple" and has only
         character information item content (see [REC-XML-INFOSET]). For
         example, the search string "julian" would match defined when the
         DAV:displayname property with Depth header has value "Julian Reschke". "0";
      other values result in a 400 (Bad Request) error response. Note
      that [RFC3253], Section 3.6, states that if the on-the-wire marshalling Depth header is
      not present, it defaults to a value of DAV:displayname in this case is:
         <D:displayname xmlns:D="DAV:">Julian Reschke</D:displayname> "0".

      The name of the property is encoded into the response body MUST be  a DAV:principal-search-property-set XML
      element, containing a DAV:principal-search-property XML element
         information item, and the character information item content of
         the
      for each property is "Julian Reschke".

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 45] that may be searched with the
      DAV:principal-property-search REPORT. A more complicated case occurs when properties have mixed content
         (that is, compound values consisting of multiple child element
         items, other types server MAY limit its
      response to just a subset of information items, the searchable properties, such as
      those likely to be useful to an interactive access control client.

      <!ELEMENT principal-search-property-set
       (principal-search-property*) >

      Each DAV:principal-search-property XML element contains exactly
      one searchable property, and character information
         item content). Consider a description of the property.

      <!ELEMENT principal-search-property (prop, description) >

      The DAV:prop element contains one principal property "aprop" in on which the namespace
         "http://www.example.com/props/", marshalled as:
         <W:aprop xmlns:W="http://www.example.com/props/">
         {cdata 0}<W:elem1>{cdata 1}</W:elem1>
           <W:elem2>{cdata 2}</W:elem2>{cdata 3}
         </W:aprop>

         In this case, matching
      server is performed on each individual contiguous
         sequence able to perform a DAV:principal-property-search REPORT.

      prop: see RFC 2518, Section 12.11

      The description element is a human-readable description of character what
      information items. In this property represents. Servers MUST indicate the example above, a
         search string would be compared to
      human language of the four following strings:
         {cdata 0}
         {cdata 1}
         {cdata 2}
         {cdata 3}

         That is, four individual matches would be performed, one each for
         {cdata 0}, {cdata 1}, {cdata 2}, description using the xml:lang attribute and {cdata 3}.

    9.4.2
      SHOULD consider the HTTP Accept-Language request header when
      selecting one of multiple available languages.

      <!ELEMENT description #PCDATA >

9.5.1 Example: successful DAV:principal-property-search DAV:principal-search-property-set REPORT

   In this example, the client requests determines the principal URLs set of all
         users whose DAV:displayname property contains the substring "doE"
         and whose "title" property in the namespace
         "http://BigCorp.com/ns/" (that is, their professional title)
         contains "Sales".  In addition, the client requests five
         properties to be returned with the matching principals:
         In the DAV: namespace: displayname
         In the http://www.example.com/ns/ namespace: department, phone,
         office, salary
         The response shows that two principal resources meet the search
         specification, "John Doe" and "Zygdoebert Smith". The property
         "salary" in namespace "http://www.example.com/ns/" is not
         returned, since the searchable
   principal making the request does not have
         sufficient access permissions to read this property. properties by requesting the
   DAV:principal-search-property-set REPORT on the root of the server's
   principal URL collection set, identified by http://www.example.com/
   users/.

   >> Request <<

   REPORT /users/ HTTP/1.1
   Host: www.example.com
   Content-Type: text/xml; charset=utf-8 charset="utf-8"
   Content-Length: xxxx xxx
   Accept-Language: en, de
   Authorization: BASIC d2FubmFtYWs6cGFzc3dvcmQ=
   Depth: 0

   <?xml version="1.0" encoding="utf-8" ?>
         <D:principal-property-search xmlns:D="DAV:">
           <D:property-search>
             <D:prop>
               <D:displayname/>
             </D:prop>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 46] 
             <D:match>doE</D:match>
           </D:property-search>
           <D:property-search>
             <D:prop xmlns:B="http://www.example.com/ns/">
               <B:title/>
             </D:prop>
             <D:match>Sales</D:match>
           </D:property-search>
           <D:prop xmlns:B="http://www.example.com/ns/">
             <D:displayname/>
             <B:department/>
             <B:phone/>
             <B:office/>
             <B:salary/>
           </D:prop>
         </D:principal-property-search>
   <D:principal-search-property-set xmlns:D="DAV:"/>
   >> Response <<

   HTTP/1.1 207 Multi-Status 200 OK
   Content-Type: text/xml; charset=utf-8 charset="utf-8"
   Content-Length: xxxx xxx

   <?xml version="1.0" encoding="utf-8" ?>
         <D:multistatus xmlns:D="DAV:" xmlns:B="http://BigCorp.com/ns/">
           <D:response>
             <D:href>http://www.example.com/users/jdoe</D:href>
             <D:propstat>
               <D:prop>
                 <D:displayname>John Doe</D:displayname>
                 <B:department>Widget Sales</B:department>
                 <B:phone>234-4567</B:phone>
                 <B:office>209</B:office>
               </D:prop>
               <D:status>HTTP/1.1 200 OK</D:status>
             </D:propstat>
             <D:propstat>
               <D:prop>
                 <B:salary/>
               </D:prop>
               <D:status>HTTP/1.1 403 Forbidden</D:status>
             </D:propstat>
           </D:response>
           <D:response>
             <D:href>http://www.example.com/users/zsmith</D:href>
             <D:propstat>
   <D:principal-search-property-set xmlns:D="DAV:">
     <D:principal-search-property>
       <D:prop>
                 <D:displayname>Zygdoebert Smith</D:displayname>
                 <B:department>Gadget Sales</B:department>
                 <B:phone>234-7654</B:phone>
                 <B:office>114</B:office>
         <D:displayname/>
       </D:prop>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 47] 
               <D:status>HTTP/1.1 200 OK</D:status>
             </D:propstat>
             <D:propstat>
               <D:prop>
                 <B:salary/>
       <D:description xml:lang="en">Full name</D:description>
     </D:principal-search-property>
     <D:principal-search-property>
       <D:prop xmlns:B="http://BigCorp.com/ns/">
         <B:title/>
       </D:prop>
               <D:status>HTTP/1.1 403 Forbidden</D:status>
             </D:propstat>
           </D:response>
         </D:multistatus>

    9.5 DAV:principal-search-property-set REPORT

         The DAV:principal-search-property-set REPORT identifies those
         properties that may be searched using the DAV:principal-property-
         search REPORT (defined in Section 9.4).
         Servers
       <D:description xml:lang="en">Job title</D:description>
     </D:principal-search-property>
   </D:principal-search-property-set>

10. XML Processing

   Implementations of this specification MUST support the DAV:principal-search-property-set REPORT
         on all collections identified XML element
   ignore rule, as specified in the value Section 23.3.2 of a DAV:principal-
         collection-set property.
         An access control protocol user agent could use [RFC2518], and the results XML
   Namespace recommendation [REC-XML-NAMES].

   Note that use of the
         DAV:principal-search-property-set REPORT to present a query
         interface to the user for retrieving principals.
         Support for this report DAV namespace is REQUIRED.
           Implementation Note: Some clients will have only limited screen
           real estate reserved for the display of lists of searchable properties.
           In this case, XML elements and
   property names defined in a user might appreciate having standards-track or Experimental IETF RFC.

11. Internationalization Considerations

   In this specification, the most
           frequently searched properties only human-readable content can be displayed on-screen, rather
           than having to scroll through a long list of searchable
           properties. One mechanism for signaling found
   in the most frequently
           searched properties is to return them towards description XML element, found within the start of
   DAV:supported-privilege-set property.  This element contains a
           list
   human-readable description of properties. A client can then preferentially display the list capabilities controlled by a
   privilege.  As a result, the description element must be capable of properties
   representing descriptions in order, increasing multiple character sets.  Since the likelihood that
   description element is found within a WebDAV property, it is
   represented on the most frequently searched properties will appear on-screen, wire as XML [REC-XML], and will not require scrolling for their selection.
       Marshalling:
         The request body MUST be an empty DAV:principal-search-property- hence can leverage
   XML's language tagging and character set encoding capabilities.
   Specifically, XML element.
         This report is only defined when processors at minimum must be able to read XML
   elements encoded using the Depth header has value "0";
         other values result UTF-8 [RFC3629] encoding of the ISO 10646
   multilingual plane. XML examples in a 400 (Bad Request) error response. Note
         that [RFC3253], Section 3.6, states that if this specification demonstrate
   use of the Depth header is
         not present, it defaults to a value charset parameter of "0".
         The response body MUST be  a DAV:principal-search-property-set XML
         element, containing a DAV:principal-search-property the Content-Type header, as defined
   in [RFC3023], as well as the XML element "encoding" attribute, which together
   provide charset identification information for each property that may be searched MIME and XML
   processors. Futhermore, this specification requires server
   implementations to tag description fields with the DAV:principal-
         property-search REPORT. A xml:lang attribute
   (see Section 2.12 of [REC-XML]), which specifies the human language
   of the description. Additionally, server MAY limit its response to just a
         subset implementations should take
   into account the value of the searchable properties, such as those likely Accept-Language HTTP header to be
         useful
   determine which description string to an interactive access control client.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 48] 
         <!ELEMENT principal-search-property-set (principal-search-
         property*) >

         Each DAV:principal-search-property return.

   For XML element contains exactly
         one searchable property, and a elements other than the description of element, it is expected
   that implementations will treat the property.
         <!ELEMENT principal-search-property (prop, description) >

         The DAV:prop element contains one principal property on which names, privilege names,
   and values as tokens, and convert these tokens into human-readable
   text in the
         server is able user's language and character set when displayed to perform a DAV:principal-property-search REPORT.
         prop: see RFC 2518, Section 12.11

         The description element is
   person.  Only a human-readable description of what
         information this generic WebDAV property represents. Servers MUST indicate the display utility would display
   these values in their raw form to a human language of user.

   For error reporting, we follow the convention of HTTP/1.1 status
   codes, including with each status code a short, English description using
   of the xml:lang attribute code (e.g., 200 (OK)).  While the possibility exists that a
   poorly crafted user agent would display this message to a user,
   internationalized applications will ignore this message, and
         SHOULD consider display
   an appropriate message in the HTTP Accept-Language request header when
         selecting one user's language and character set.

   Further internationalization considerations for this protocol are
   described in the WebDAV Distributed Authoring protocol specification
   [RFC2518].

12. Security Considerations

   Applications and users of multiple available languages.
         <!ELEMENT description #PCDATA >

    9.5.1 Example: DAV:principal-search-property-set REPORT

         In this example, the client determines the set access control protocol should be
   aware of searchable
         principal properties by requesting several security considerations, detailed below. In addition
   to the DAV:principal-search-
         property-set REPORT on discussion in this document, the root of security considerations
   detailed in the server's principal URL
         collection set, identified by http://www.example.com/users/.
         >> Request <<
         REPORT /users/ HTTP/1.1
         Host: www.example.com
         Content-Type: text/xml; charset="utf-8"
         Content-Length: xxx
         Accept-Language: en, de
         Authorization: BASIC d2FubmFtYWs6cGFzc3dvcmQ=
         Depth: 0

         <?xml version="1.0" encoding="utf-8" ?>
         <D:principal-search-property-set xmlns:D="DAV:"/>

         >> Response << HTTP/1.1 200 OK
         Content-Type: text/xml; charset="utf-8"
         Content-Length: xxx

         <?xml version="1.0" encoding="utf-8" ?>
         <D:principal-search-property-set xmlns:D="DAV:">
           <D:principal-search-property>
             <D:prop>
               <D:displayname/>
             </D:prop>
             <D:description xml:lang="en">Full name</D:description>
           </D:principal-search-property>
           <D:principal-search-property>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 49] 
             <D:prop xmlns:B="http://BigCorp.com/ns/">
               <B:title/>
             </D:prop>
             <D:description xml:lang="en">Job title</D:description>
           </D:principal-search-property>
         </D:principal-search-property-set>

    10 XML PROCESSING

         Implementations of this specification MUST support [RFC2616], the XML element
         ignore rule, as specified in Section 23.3.2 of WebDAV
   Distributed Authoring Protocol specification [RFC2518], and the XML Namespace recommendation [REC-XML-NAMES].
         Note that use of the DAV namespace is reserved for XML elements
         and property names defined
   Media Types specification [RFC3023] should be considered in a standards-track or Experimental
         IETF RFC.

    11 INTERNATIONALIZATION CONSIDERATIONS

         In
   security analysis of this specification, protocol.

12.1 Increased Risk of Compromised Users

   In the absence of a mechanism for remotely manipulating access
   control lists, if a single user's authentication credentials are
   compromised, only human-readable content those resources for which the user has access
   permission can be
         found in read, modified, moved, or deleted. With the description XML element, found within
   introduction of this access control protocol, if a single compromised
   user has the
         DAV:supported-privilege-set property.  This element contains ability to change ACLs for a
         human-readable description broad range of other users
   (e.g., a super-user), the capabilities controlled number of resources that could be altered
   by a
         privilege.  As a result, the description element must single compromised user increases. This risk can be capable
         of representing descriptions in multiple character sets.  Since mitigated by
   limiting the description element is found within number of people who have write-acl privileges across a WebDAV property, it is
         represented on
   broad range of resources.

12.2 Risks of the wire as XML [REC-XML], and hence can leverage
         XML's language tagging DAV:read-acl and character set encoding capabilities.
         Specifically, XML processors at minimum must be able DAV:current-user-privilege-set
     Privileges

   The ability to read XML
         elements encoded using the UTF-8 [UTF-8] encoding of access privileges (stored in the ISO 10646
         multilingual plane. XML examples DAV:acl
   property), or the privileges permitted the currently authenticated
   user (stored in this specification demonstrate
         use of the charset parameter of DAV:current-user-privilege-set property) on a
   resource may seem innocuous, since reading an ACL cannot possibly
   affect the Content-Type header, as
         defined resource's state. However, if all resources have
   world-readable ACLs, it is possible to perform an exhaustive search
   for those resources that have inadvertently left themselves in [RFC3023], as well a
   vulnerable state, such as being world-writeable. In particular, the XML "encoding" attribute,
         which together provide charset identification information for MIME
         and XML processors. Futhermore, this specification requires server
         implementations to tag description fields
   property retrieval method PROPFIND, executed with the xml:lang
         attribute (see Section 2.12 of [REC-XML]), which specifies the
         human language of the description. Additionally, server
         implementations should take into account the value of the Accept-
         Language HTTP header Depth infinity on
   an entire hierarchy, is a very efficient way to determine retrieve the DAV:acl
   or DAV:current-user-privilege-set properties. Once found, this
   vulnerability can be exploited by a denial of service attack in which description string to
         return.
         For XML elements other than
   the description element, it open resource is
         expected that implementations will treat the property names,
         privilege names, and values as tokens, and convert these tokens
         into human-readable text repeatedly overwritten. Alternately, writeable
   resources can be modified in the user's language undesirable ways.

   To reduce this risk, read-acl privileges should not be granted to
   unauthenticated principals, and character set restrictions on read-acl and
   read-current-user-privilege-set privileges for authenticated
   principals should be carefully analyzed when displayed to a person.  Only a generic WebDAV property
         display utility would display these values in their raw form deploying this protocol.
   Access to a
         human user.
         For error reporting, we follow the convention of HTTP/1.1 status
         codes, including with each status code current-user-privilege-set property will involve a short, English
         description
   tradeoff of usability versus security. When the code (e.g., 200 (OK)).  While the possibility

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 50] 
         exists that a poorly crafted
   current-user-privilege-set is visible, user agent would display this message interfaces are expected
   to a user, internationalized applications will ignore this
         message, and display an appropriate message in the user's language provide enhanced information concerning permitted and character set.
         Further internationalization considerations for restricted
   operations, yet this information may also indicate a vulnerability
   that could be exploited. Deployment of this protocol are
         described will need to
   evaluate this tradeoff in light of the WebDAV Distributed Authoring protocol
         specification [RFC2518].

    12 SECURITY CONSIDERATIONS

         Applications and users requirements of this access control protocol should be
         aware the deployment
   environment.

12.3 No Foreknowledge of several security considerations, detailed below. Initial ACL

   In
         addition an effort to the discussion in reduce protocol complexity, this document, the security
         considerations detailed in the HTTP/1.1 specification [RFC2616],
         the WebDAV Distributed Authoring Protocol protocol
   specification [RFC2518],
         and intentionally does not address the XML Media Types specification [RFC3023] should be
         considered in a security analysis of this protocol.

    12.1 Increased Risk issue of Compromised Users

         In how to
   manage or discover the absence of a mechanism for remotely manipulating access
         control lists, if initial ACL that is placed upon a single user's authentication credentials are
         compromised, resource
   when it is created. The only those resources for which way to discover the user has access
         permission can be read, modified, moved, or deleted. With initial ACL is to
   create a new resource, then retrieve the
         introduction value of this access control protocol, if a single
         compromised user the DAV:acl
   property. This assumes the principal creating the resource also has
   been granted the ability to change ACLs for DAV:read-acl privilege.

   As a broad range
         of other users (e.g., result, it is possible that a super-user), the number of resources principal could create a resource,
   and then discover that its ACL grants privileges that are
   undesirable. Furthermore, this protocol makes it possible (though
   unlikely) that the creating principal could be altered by unable to modify the
   ACL, or even delete the resource. Even when the ACL can be modified,
   there will be a single compromised user increases. This risk short period of time when the resource exists with
   the initial ACL before its new ACL can be mitigated by set.

   Several factors mitigate this risk. Human principals are often aware
   of the default access permissions in their editing environments and
   take this into account when writing information. Furthermore, default
   privilege policies are usually very conservative, limiting the number of people who have write-
         acl
   privileges across a broad range of resources.

    12.2 Risks of granted by the DAV:read-acl initial ACL.

13. Authentication

   Authentication mechanisms defined for use with HTTP and DAV:current-user-privilege-set
        Privileges

         The ability WebDAV also
   apply to read this WebDAV Access Control Protocol, in particular the access privileges (stored Basic
   and Digest authentication mechanisms defined in [RFC2617].
   Implementation of the DAV:acl
         property), or ACL spec requires that Basic authentication, if
   used, MUST only be supported over secure transport such as TLS.

14. IANA Considerations

   This document uses the privileges permitted namespace defined by [RFC2518] for XML
   elements. That is, this specification uses the currently authenticated
         user (stored "DAV:" URI namespace,
   previously registered in the DAV:current-user-privilege-set property) on a
         resource may seem innocuous, since reading an URI schemes registry. All other IANA
   considerations mentioned in [RFC2518] are also applicable to this
   specification.

15. Acknowledgements

   This protocol is the collaborative product of the WebDAV ACL cannot possibly
         affect design
   team: Bernard Chester, Geoff Clemm, Anne Hopkins, Barry Lind, Sean
   Lyndersay, Eric Sedlar, Greg Stein, and Jim Whitehead. The authors
   are grateful for the resource's state. However, if all resources have world-
         readable ACLs, it is possible to perform an exhaustive search detailed review and comments provided by Jim
   Amsden, Dylan Barrell, Gino Basso, Murthy Chintalapati, Lisa
   Dusseault, Stefan Eissing, Tim Ellison, Yaron Goland, Dennis
   Hamilton, Laurie Harper, Eckehard Hermann, Ron Jacobs, Chris Knight,
   Remy Maucherat, Larry Masinter, Joe Orton, Peter Raymond, Julian
   Reschke, and Keith Wannamaker. We thank Keith Wannamaker for
         those resources that have inadvertently left themselves in a
         vulnerable state, such as being world-writeable. In particular, the
   initial text of the principal property retrieval method PROPFIND, executed with Depth
         infinity search sections. Prior work on an entire hierarchy, is a very efficient way
   WebDAV access control protocols has been performed by Yaron Goland,
   Paul Leach, Lisa Dusseault, Howard Palmer, and Jon Radoff. We would
   like to
         retrieve acknowledge the DAV:acl or DAV:current-user-privilege-set properties.
         Once found, this vulnerability can be exploited foundation laid for us by a denial the authors of
         service attack in which the open resource
   DeltaV, WebDAV and HTTP protocols upon which this protocol is repeatedly
         overwritten. Alternately, writeable resources can be modified
   layered, and the invaluable feedback from the WebDAV working group.

Normative References

   [REC-XML]  Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
              "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC
              REC-xml-20001006, October 2000, <http://www.w3.org/TR/
              2000/REC-xml-20001006>.

   [REC-XML-INFOSET]
              Cowan, J. and R. Tobin, "XML Information Set", W3C REC
              REC-xml-infoset-20011024, October 2001, <http://
              www.w3.org/TR/2001/REC-xml-infoset-20011024>.

   [REC-XML-NAMES]
              Bray, T., Hollander, D. and A. Layman, "Namespaces in
         undesirable ways.
         To reduce this risk, read-acl privileges should not be granted
              XML", W3C REC REC-xml-names-19990114, January 1999,
              <http://www.w3.org/TR/1999/REC-xml-names-19990114>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to
         unauthenticated principals, and restrictions on read-acl Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2518]  Goland, Y., Whitehead, E., Faizi, A., Carter, S. and read-
         current-user-privilege-set privileges D.
              Jensen, "HTTP Extensions for authenticated principals
         should be carefully analyzed when deploying this protocol. Distributed Authoring --
              WEBDAV", RFC 2518, February 1999.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A. and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC3023]  Makoto, M., St.Laurent, S. and D. Kohn, "XML Media Types",
              RFC 3023, January 2001.

   [RFC3253]  Clemm, Hopkins, Sedlar, Whitehead                                [Page 51] 
         to the current-user-privilege-set property will involve a tradeoff
         of usability versus security. When the current-user-privilege-set
         is visible, user interfaces are expected to provide enhanced
         information concerning permitted G., Amsden, J., Ellison, T., Kaler, C. and restricted operations, yet
         this information may also indicate a vulnerability that could be
         exploited. Deployment of this protocol will need to evaluate this
         tradeoff in light of the requirements of the deployment
         environment.

    12.3 No Foreknowledge of Initial ACL

         In an effort to reduce protocol complexity, this protocol
         specification intentionally does not address the issue of how to
         manage or discover the initial ACL that is placed upon a resource
         when it is created. The only way to discover the initial ACL is J.
              Whitehead, "Versioning Extensions to
         create WebDAV", RFC 3253,
              March 2002.

   [RFC3530]  Shepler, S., Ed., Callaghan, B., Robinson, D., Thurlow,
              R., Beame, C., Eisler, M. and D. Noveck, "Network File
              System (NFS) version 4 Protocol", RFC 3530, April 2003.

   [RFC3629]  Yergeau, F., "UTF-8, a new resource, then retrieve the value transformation format of the DAV:acl
         property. This assumes the principal creating the resource also
         has been granted the DAV:read-acl privilege.
         As a result, it is possible that a principal could create a
         resource, ISO
              10646", RFC 3629, STD 63, November 2003.

Informative References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

   [RFC2251]  Wahl, M., Howes, T. and then discover that its ACL grants privileges that
         are undesirable. Furthermore, S. Kille, "Lightweight Directory
              Access Protocol (v3)", RFC 2251, December 1997.

   [RFC2255]  Howes, T. and M. Smith, "The LDAP URL Format", RFC 2255,
              December 1997.

   [UNICODE4]
              The Unicode Consortium, "The Unicode Standard - Version
              4.0", Addison-Wesley , August 2003, <http://
              www.unicode.org/versions/Unicode4.0.0/>.

              ISBN 0321185781 [4].

URIs

   [1]  <mailto:acl@webdav.org>

   [2]  <http://www.example.com/acl/>

   [3]  <http://www.ics.uci.edu/pub/ietf/webdav/>

   [4]  <urn:isbn:0321185781>

Authors' Addresses

   G. Clemm
   IBM
   20 Maguire Road
   Lexington, MA  02421

   EMail: geoffrey.clemm@us.ibm.com

   Julian F. Reschke
   greenbytes GmbH
   Salzmannstrasse 152
   Muenster, NW  48159
   Germany

   EMail: julian.reschke@greenbytes.de

   E. Sedlar
   Oracle Corporation
   500 Oracle Parkway
   Redwood Shores, CA  94065

   EMail: eric.sedlar@oracle.com
   J. Whitehead
   U.C. Santa Cruz, Dept. of Computer Science
   1156 High Street
   Santa Cruz, CA  95064

   EMail: ejw@cse.ucsc.edu

Appendix A. WebDAV XML Document Type Definition Addendum

   All XML elements defined in this protocol makes it possible
         (though unlikely) that the creating principal could be unable Document Type Definition (DTD)
   belong to
         modify the ACL, or even delete the resource. Even when the ACL can
         be modified, there will be a short period of time when the
         resource exists with the initial ACL before its new ACL can DAV namespace. This DTD should be
         set.
         Several factors mitigate this risk. Human principals are often
         aware of viewed as an addendum
   to the default access permissions DTD provided in their editing
         environments and take this into account when writing information.
         Furthermore, default [RFC2518], section 23.1.

   <!-- Privileges -- (Section 3)>

   <!ELEMENT read EMPTY>
   <!ELEMENT write EMPTY>
   <!ELEMENT write-properties EMPTY>
   <!ELEMENT write-content EMPTY>
   <!ELEMENT unlock EMPTY>
   <!ELEMENT read-acl EMPTY>
   <!ELEMENT read-current-user-privilege-set EMPTY>
   <!ELEMENT write-acl EMPTY>
   <!ELEMENT bind EMPTY>
   <!ELEMENT unbind EMPTY>
   <!ELEMENT all EMPTY>

   <!-- Principal Properties (Section 4) -->

   <!ELEMENT principal EMPTY>

   <!ELEMENT alternate-URI-set (href*)>
   <!ELEMENT principal-URL (href)>
   <!ELEMENT group-member-set (href*)>
   <!ELEMENT group-membership (href*)>

   <!-- Access Control Properties (Section 5) -->

   <!-- DAV:owner Property (Section 5.1) -->

   <!ELEMENT owner (href?)>

   <!-- DAV:group Property (Section 5.2) -->

   <!ELEMENT group (href?)>
   <!-- DAV:supported-privilege-set Property (Section 5.3) -->

   <!ELEMENT supported-privilege-set (supported-privilege*)>
   <!ELEMENT supported-privilege
    (privilege, abstract?, description, supported-privilege*)>

   <!ELEMENT privilege ANY>
   <!ELEMENT abstract EMPTY>
   <!ELEMENT description #PCDATA>

   <!-- DAV:current-user-privilege-set Property (Section 5.4) -->

   <!ELEMENT current-user-privilege-set (privilege*)>

   <!-- DAV:acl Property (Section 5.5) -->

   <!ELEMENT acl (ace)* >
   <!ELEMENT ace ((principal | invert), (grant|deny), protected?,
    inherited?)>

   <!ELEMENT principal (href)
    | all | authenticated | unauthenticated
    | property | self)>

   <!ELEMENT all EMPTY>
   <!ELEMENT authenticated EMPTY>
   <!ELEMENT unauthenticated EMPTY>
   <!ELEMENT property ANY>
   <!ELEMENT self EMPTY>

   <!ELEMENT invert principal>

   <!ELEMENT grant (privilege+)>
   <!ELEMENT deny (privilege+)>
   <!ELEMENT privilege policies are usually very
         conservative, limiting the privileges granted by the initial ACL.

    13 AUTHENTICATION

         Authentication mechanisms defined for use with HTTP and WebDAV
         also apply to this WebDAV ANY>

   <!ELEMENT protected EMPTY>

   <!ELEMENT inherited (href)>
   <!-- DAV:acl-restrictions Property (Section 5.6) -->

   <!ELEMENT acl-restrictions (grant-only?, no-invert?,
    deny-before-grant?, required-principal?)>

   <!ELEMENT grant-only EMPTY>
   <!ELEMENT no-invert EMPTY>
   <!ELEMENT deny-before-grant EMPTY>

   <!ELEMENT required-principal
    (all? | authenticated? | unauthenticated? | self? | href*
    |property*)>

   <!-- DAV:inherited-acl-set Property (Section 5.7) -->

   <!ELEMENT inherited-acl-set (href*)>

   <!-- DAV:principal-collection-set Property (Section 5.8) -->

   <!ELEMENT principal-collection-set (href*)>

   <!-- Access Control Protocol, in particular
         the Basic and Digest authentication mechanisms defined in
         [RFC2617].  Implementation of the Existing Methods (Section 7) -->

   <!ELEMENT need-privileges (resource)* >
   <!ELEMENT resource ( href, privilege )

   <!-- ACL spec requires that Basic
         authentication, if used, MUST only be supported over secure
         transport such as TLS.

    14 IANA CONSIDERATIONS

         This document uses the namespace defined by [RFC2518] for XML
         elements. That is, this specification uses the "DAV:" URI
         namespace, previously registered in the URI schemes registry. All
         other IANA considerations mentioned in [RFC2518] are also
         applicable to this specification.

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 52] 
    15 INTELLECTUAL PROPERTY method preconditions (Section 8.1.1) -->

   <!ELEMENT no-ace-conflict EMPTY>
   <!ELEMENT no-protected-ace-conflict EMPTY>
   <!ELEMENT no-inherited-ace-conflict EMPTY>
   <!ELEMENT limited-number-of-aces EMPTY>
   <!ELEMENT grant-only EMPTY>
   <!ELEMENT no-invert EMPTY>
   <!ELEMENT deny-before-grant EMPTY>
   <!ELEMENT no-abstract EMPTY>
   <!ELEMENT not-supported-privilege EMPTY>
   <!ELEMENT missing-required-principal EMPTY>
   <!ELEMENT recognized-principal EMPTY>
   <!ELEMENT allowed-principal EMPTY>
   <!-- REPORTs (Section 9) -->

   <!ELEMENT acl-principal-prop-set ANY>
   ANY value: a sequence of one or more elements, with at most one
   DAV:prop element.

   <!ELEMENT principal-match ((principal-property | self), prop?)>
   <!ELEMENT principal-property ANY>
   ANY value: an element whose value identifies a property. The following notice
   expectation is copied from RFC 2026, section 10.4, and
         describes the position value of the IETF concerning intellectual
         property claims made against this document.
         The IETF takes no position regarding the validity or scope of any
         intellectual named property or other rights that might be claimed to
         pertain to the implementation or use other technology described in
         this document or the extent to which any license under such rights
         might or might not be available; neither does it represent typically contains
   an href element that it
         has made any effort to identify any such rights.  Information on
         the IETF's procedures with respect to rights in standards-track
         and standards-related documentation can be found in BCP-11. Copies
         of claims of rights made available for publication and any
         assurances of licenses to be made available, or contains the result URI of an
         attempt made to obtain a general license or permission for the use
         of such proprietary rights by implementers or users principal
   <!ELEMENT self EMPTY>

   <!ELEMENT principal-property-search ((property-search+), prop?) >
   <!ELEMENT property-search (prop, match) >
   <!ELEMENT match #PCDATA >

   <!ELEMENT principal-search-property-set (
    principal-search-property*) >
   <!ELEMENT principal-search-property (prop, description) >
   <!ELEMENT description #PCDATA >

Appendix B. WebDAV Method Privilege Table (Normative)

   The following table of this
         specification can be obtained from WebDAV methods (as defined in RFC 2518, 2616,
   and 3253) clarifies which privileges are required for access for each
   method.  Note that the IETF Secretariat.
         The IETF invites any interested party to bring privileges listed, if denied, MUST cause
   access to its attention
         any copyrights, patents or patent applications, or other
         proprietary rights that may cover technology that may be required denied.  However, given that a specific implementation
   MAY define an additional custom privilege to practice this standard.  Please address the information control access to the
         IETF Executive Director.

    16 ACKNOWLEDGEMENTS

         This protocol is the collaborative product
   existing methods, having all of the WebDAV ACL
         design team: Bernard Chester, Geoff Clemm, Anne Hopkins, Barry
         Lind, Sean Lyndersay, Eric Sedlar, Greg Stein, and Jim Whitehead.
         The authors are grateful for indicated privileges does not
   mean that access will be granted.  Note that lack of the detailed review and comments
         provided by Jim Amsden, Dylan Barrell, Gino Basso, Murthy
         Chintalapati, Lisa Dusseault, Stefan Eissing, Tim Ellison, Yaron
         Goland, Dennis Hamilton, Laurie Harper, Eckehard Hermann, Ron
         Jacobs, Chris Knight, Remy Maucherat, Larry Masinter, Joe Orton,
         Peter Raymond, Julian Reschke, and Keith Wannamaker. We thank
         Keith Wannamaker for indicated
   privileges does not imply that access will be denied, since a
   particular implementation may use a sub-privilege aggregated under
   the initial text of indicated privilege to control access.  Privileges required refer
   to the principal property
         search sections. Prior work current resource being processed unless otherwise specified.

   +---------------------------------+---------------------------------+
   | METHOD                          | PRIVILEGES                      |
   +---------------------------------+---------------------------------+
   | GET                             | <D:read>                        |
   | HEAD                            | <D:read>                        |
   | OPTIONS                         | <D:read>                        |
   | PUT (target exists)             | <D:write-content> on target     |
   |                                 | resource                        |
   | PUT (no target exists)          | <D:bind> on WebDAV access control protocols has
         been performed by Yaron Goland, Paul Leach, Lisa Dusseault, Howard
         Palmer, and Jon Radoff. We would like to acknowledge the
         foundation laid for us by the authors parent collection   |
   |                                 | of the DeltaV, WebDAV target                       |
   | PROPPATCH                       | <D:write-properties>            |
   | ACL                             | <D:write-acl>                   |
   | PROPFIND                        | <D:read> (plus <D:read-acl> and
         HTTP protocols upon which this protocol is layered, |
   |                                 | <D:read-current-user-privilege- |
   |                                 | set> as needed)                 |
   | COPY (target exists)            | <D:read>, <D:write-content> and the
         invaluable feedback from the WebDAV working group.

    17 REFERENCES

    17.1 Normative References

         [RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
         Requirement Levels." RFC 2119, BCP 14, March, 1997.
         [REC-XML] T. Bray, J. Paoli, C.M. Sperberg-McQueen, "Extensible
         Markup Language (XML)." World Wide Web Consortium Recommendation
         REC-xml.http://www.w3.org/TR/REC-xml

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 53] 
         [REC-XML-NAMES] T. Bray, D. Hollander, A. Layman, "Name Spaces in
         XML" World Wide Web Consortium Recommendation REC-xml-names.
         http://www.w3.org/TR/REC-xml-names/
         [RFC3253] G. Clemm, J. Amsden, T. Ellison, C. Kaler, J. Whitehead,
         "Versioning Extensions to WebDAV." RFC 3253, March 2002.
         [REC-XML-INFOSET] J. Cowan, R. Tobin, "XML Information Set." World
         Wide Web Consortium Recommendation REC-xml-infoset.
         http://www.w3.org/TR/xml-infoset/
         [RFC2616] R. Fielding, J. Gettys, J. C. Mogul, H. Frystyk, L.
         Masinter, P. Leach, |
   |                                 | <D:write-properties> on target  |
   |                                 | resource                        |
   | COPY (no target exists)         | <D:read>, <D:bind> on target    |
   |                                 | collection                      |
   | MOVE (no target exists)         | <D:unbind> on source collection |
   |                                 | and T. Berners-Lee, "Hypertext Transfer
         Protocol -- HTTP/1.1." RFC 2616, June, 1999.
         [RFC2617] J. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence,
         P. Leach, A. Luotonen, L. Stewart, "HTTP Authentication: Basic <D:bind> on target          |
   |                                 | collection                      |
   | MOVE (target exists)            | As above, plus <D:unbind> on    |
   |                                 | the target collection           |
   | DELETE                          | <D:unbind> on parent collection |
   | LOCK (target exists)            | <D:write-content>               |
   | LOCK (no target exists)         | <D:bind> on parent collection   |
   | MKCOL                           | <D:bind> on parent collection   |
   | UNLOCK                          | <D:unlock>                      |
   | CHECKOUT                        | <D:write-properties>            |
   | CHECKIN                         | <D:write-properties>            |
   | REPORT                          | <D:read> (on all referenced     |
   |                                 | resources)                      |
   | VERSION-CONTROL                 | <D:write-properties>            |
   | MERGE                           | <D:write-content>               |
   | MKWORKSPACE                     | <D:write-content> on parent     |
   |                                 | collection                      |
   | BASELINE-CONTROL                | <D:write-properties> and
         Digest Access Authentication." RFC 2617, June, 1999.
         [RFC2518] Y. Goland, E. Whitehead, A. Faizi, S. R. Carter, D.
         Jensen, "HTTP Extensions for Distributed Authoring -- WEBDAV." RFC
         2518, February, 1999.
         [RFC2368] P. Hoffman, L. Masinter, J. Zawinski, "The mailto URL
         scheme." RFC 2368, July, 1998.
         [RFC3023] M. Murata, S. St.Laurent, D. Kohn, "XML Media Types."
         RFC 3023, January, 2001.
         [RFC3010] S. Shepler, B. Callaghan, D. Robinson, R. Thurlow,        |
   |                                 | <D:write-content>               |
   | MKACTIVITY                      | <D:write-content> on parent     |
   |                                 | collection                      |
   +---------------------------------+---------------------------------+

Appendix C.
         Beame, M. Eisler, D.Noveck "NFS version 4 Protocol." Resolved issues (to be removed by RFC 3010,
         December 2000.
          [UTF-8] F. Yergeau, "UTF-8, a transformation format Editor before
            publication)
   Issues that were either rejected or resolved in this version of Unicode
         and ISO 10646." RFC 2279, January, 1998.

    17.2 Informational References

         [RFC2026] S.Bradner, "The Internet Standards Process - Revision
         3." RFC 2026, BCP 9. Harvard, October, 1996.
         [RFC2255] T. Howes, M. Smith, "The LDAP URL Format." RFC 2255.
         Netscape, December, 1997.
         [RFC2251] M. Wahl, T. Howes, S. Kille, "Lightweight Directory
         Access Protocol (v3)." RFC 2251. Critical Angle, Netscape, Isode,
         December, 1997.
         [CaseMap] M. Davis, "Case Mappings", Unicode Standard Annex #21,
         March 26, 2001.  http://www.unicode.org/unicode/reports/tr21

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 54] 
    18 AUTHORS' ADDRESSES

         Geoffrey Clemm
         IBM
         20 Maguire Road
         Lexington, MA 02421
         Email: this
   document.

C.1 ED_references_names

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): Replace "Informative
   References" by "Informational References".

   Resolution (2003-11-06): Section title renamed from "Informative
   References" to "Informational References" (no change tracking).

C.2 ED_RFC2386

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): RFC2386 is listed, but not
   mentioned in the spec.

   Resolution (2003-11-06): Entry RFC2386 removed from references (no
   change tracking).

C.3 ED_example_host_names

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001719.html>

   julian.reschke@greenbytes.de (2003-11-06): When changing the host
   names, we forgot to also update user names that appear in
   "Authorization" headers (such as "gclemm@webdav.org"). I'd recommend
   to just replace "@webdav.org" with "@example.com". Also fix broken
   realms (always say "users@example.com").

   Resolution (2003-11-06): All realms changed to "users@example.com".

C.4 ED_authors_list

   Type: edit

   geoffrey.clemm@us.ibm.com (2003-11-06): Remove Anne Hopkins
         Microsoft Corporation
         One Microsoft Way
         Redmond, WA 98052
         Email: annehop@microsoft.com

         Eric Sedlar
         Oracle Corporation
         500 Oracle Parkway
         Redwood Shores, CA 94065
         Email: eric.sedlar@oracle.com

         Jim Whitehead
         U.C. Santa Cruz
         Dept. from
   authors list (keep her name in the Acknowledgements section).

   geoffrey.clemm@us.ibm.com (2003-12-20): Add Julian Reschke to authors
   list.

   Resolution (2003-12-20): Removed Anne Hopkins from authors list (both
   in front page and in "authors" section). Added Julian Reschke to
   authors list.

C.5 ED_non_ASCII

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001712.html>

   julian.reschke@greenbytes.de (2003-11-03): some non-ASCII characters
   (long dashes and quotes) are present

   Resolution (2003-11-04): Fixed in Sections 3.1, 3.3, 3.4, 6, 7.1.1.

C.6 ED_artwork_line_width

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001712.html>

   julian.reschke@greenbytes.de (2003-11-03): In request/responses/DTDs,
   the line width sometimes exceeds what's allowed in an RFC (I think 72
   characters).

   Resolution (2003-11-04): Added line breaks and/or changed indention
   in some of Computer Science
         Baskin Engineering
         1156 High Street
         Santa Cruz, CA 95064
         Email: ejw@cse.ucsc.edu

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 55] 
    19 APPENDICES

    19.1 WebDAV the figures (no change tracking).

C.7 ED_xml_typos

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001712.html>

   julian.reschke@greenbytes.de (2003-11-03): There were a few typos in
   the XML Document Type Definition Addendum

         All examples

   Resolution (2003-11-04): Several XML elements defined message bodies fixed (no change
   tracking).

C.8 1_ref_options

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001718.html>
   julian.reschke@greenbytes.de (2003-11-04): "Client discovery of
   access control capability using OPTIONS is described in Section 7.1."
   The reference should be to "7.2".

   Resolution (2003-11-04): Replaced "7.1" with "7.2"

C.9 3.2_ED_RFC2518

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): Fix references
   ("[WEBDAV]") to RFC2518.

   Resolution (2003-11-05): Replaced "[WEBDAV]" by "[RFC2518]".

C.10 3.3_ED_priv_section_titles

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001741.html>

   julian.reschke@greenbytes.de (2003-11-07): Section titles for
   DAV:write-properties, DAV:write-content and DAV:unlock missing word
   "Privilege".

   Resolution (2003-11-07): Added "Privilege" to the section titles (no
   change tracking).

C.11 3.4_write-content-description

   Type: change

   <http://mailman.webdav.org/pipermail/acl/2003-November/001757.html>

   csharp@mac.com (2003-11-18): If DAV:write-content is just an
   aggregate of DAV:bind and DAV:unbind why doesn't it state that "the
   client can safely expect that no other privilege needs to be granted
   to have access to MKCOL,PUT, DELETE,MOVE, COPY"? If it is not an
   aggregate why does it exist?

   Resolution (2003-11-18): Update description of DAV:write-content so
   that it doesn't refer to collection membership; clarify the
   distinction between PUT to an existing reource (modifying content)
   and PUT on an unmapped URI (creating a new resource, requiring
   privileges on the parent collection). Define aggregation of DAV:bind
   and DAV:unbind in 3.12.

C.12 3.12_ED_bad_reference

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001712.html>

   julian.reschke@greenbytes.de (2003-11-03): section 3.12 talks about
   "defined above in Sections 3.1-3.9". I think this should be "defined
   above in Sections 3.1-3.11" or simply "defined in above sections"

   geoffrey.clemm@us.ibm.com (2003-11-06): For the section 3.12 issue,
   I'd prefer to change it to say "Sections 3.1-3.10" (the DAV:all
   privilege from section 3.11 should not be included in this Document Type Definition (DTD)
         belong to another
   privilege).

   Resolution (2003-11-06): Replace "Sections 3.1-3.9" by "Sections
   3.1-3.10".

C.13 4.1_ED_RFC2589

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): text quotes RFC2589
   ("Lightweight Directory Access Protocol (v3): Extensions for Dynamic
   Directory Services"), but references section has RFC2251
   ("Lightweight Directory Access Protocol (v3)")

   geoffrey.clemm@us.ibm.com (2003-11-06): The LDAP reference should be
   RFC2251 (not RFC2589).

   Resolution (2003-11-06): Replaced "[RFC2589]" by "[RFC2251]".

C.14 5.1_owner_group_details

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001737.html>

   julian.reschke@greenbytes.de (2003-11-07): State that DAV:owner and
   DAV:group MAY be protected. Also state that they MAY be empty if the DAV namespace. This DTD
   server can't provide the information.

   Resolution (2003-11-08): Added paragraphs stating both for both
   properties.

C.15 5.1_owner_href_optional

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001728.html>

   julian.reschke@greenbytes.de (2003-11-06): href element should be viewed as an
         addendum to
   optional in case the server doesn't have owner information.

   Resolution (2003-11-06): Updated DTD provided fragment.

C.16 5.1.2_responsedescription

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001737.html>

   julian.reschke@greenbytes.de (2003-11-07): Add DAV:error element to
   DAV:responsedescription in [RFC2518], example and update explanation.

   Resolution (2003-11-08): DAV:error subelement added to
   DAV:responsedescription in response.

C.17 5.5.5_ED_section_numbering

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001712.html>

   julian.reschke@greenbytes.de (2003-11-03): missing section 23.1.
         <!-- Privileges -- (Section 3)>

         <!ELEMENT read EMPTY>
         <!ELEMENT write EMPTY>
         <!ELEMENT write-properties EMPTY>
         <!ELEMENT write-content EMPTY>
         <!ELEMENT unlock EMPTY>
         <!ELEMENT read-acl EMPTY>
         <!ELEMENT read-current-user-privilege-set EMPTY>
         <!ELEMENT write-acl EMPTY>
         <!ELEMENT bind EMPTY>
         <!ELEMENT unbind EMPTY>
         <!ELEMENT all EMPTY>

         <!-- Principal Properties (Section 4) -->

         <!ELEMENT principal EMPTY>

         <!ELEMENT alternate-URI-set (href*)>
         <!ELEMENT principal-URL (href)>
         <!ELEMENT group-member-set (href*)>
         <!ELEMENT group-membership (href*)>

         <!-- Access Control Properties (Section 5) -->

         <!-- DAV:owner Property (Section 5.1) -->

         <!ELEMENT owner (href)>

         <!-- DAV:supported-privilege-set Property (Section 5.2) -->

         <!ELEMENT supported-privilege-set (supported-privilege*)>
         <!ELEMENT supported-privilege
          (privilege, abstract?, description, supported-privilege*)>

         <!ELEMENT numbering
   for "Example: Retrieving DAV:acl-restrictions"

   Resolution (2003-11-04): Added section number (no change tracking).

C.18 5.8_unbind

   Type: change

   <http://mailman.webdav.org/pipermail/acl/2003-November/001714.html>

   julian.reschke@greenbytes.de (2003-11-03): A:unbind: mismatch between
   XML response and privilege tree in figure.

   eric.sedlar@oracle.com (2003-11-04): The change in the XML response
   should be rolled back.  "delete" is a custom privilege in the
   example.

   Resolution (2003-11-04): Changed example response back to use
   A:delete.

C.19 6_ED_RFC3010

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): Fix references ("[NFSV4]")
   to RFC3010.

   Resolution (2003-11-11): Replaced "[NVSV4]" by "[RFC3530]" (which
   obsoletes RFC3010).

C.20 6_group_property

   Type: change

   <http://mailman.webdav.org/pipermail/acl/2003-November/001713.html>

   julian.reschke@greenbytes.de (2003-11-03): in section 6 the following
   example is used...: <D:principal><D:property><D:group/></
   D:property></D:principal> However, there is no such thing as a
   DAV:group property. I'm not sure what the best fix for this would
   be... If the "group" thing is essential, this may mean that an
   important live property is missing? If it's not essential, can this
   example rewritten without that property? (Or with a non-DAV: property
   from an example namespace?)

   geoffry.clemm@us.ibm.com (2003-11-06): Proposal to add DAV:group
   property.

   eric.sedlar@oracle.com (2003-11-06): I have a problem with adding
   this property.  If a particular vendor wants to add <vendor:group>
   that's great, but I think we are going to have minimal
   interoperability with this.  We discussed this before and weren't
   able to find anyone who actually wanted to use this.

   Resolution (2003-11-06): Added section 5.2 ("DAV:group"). Subsequent
   sections renumbered.

C.21 5.5.2_TYPO

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-October/001691.html>

   peter.nevermann@softwareag.com (2003-10-22): Precondition
   DAV:no-invert should refer to section 5.5.2 for the DAV:no-invert
   constraint ... not 6.3.4.

   Resolution (2003-11-04): Reference fixed.

C.22 9.4_ED_reference_casemap

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): Update [CaseMap] reference
   to "[UNICODE4]      The Unicode Consortium, "The Unicode Standard -
   Version 4.0", Addison-Wesley, August 2003. ISBN 0321185781" (section
   5.18).

   Resolution (2003-11-06): Removed "[CaseMap]" from references, add
   "[UNICODE]" to references. Cite using '...especially Section 2.3
   ("Caseless Matching"), Section 5.18, Subsection "Caseless
   Matching"...'.

C.23 11_ED_RFC2279

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001711.html>

   julian.reschke@greenbytes.de (2003-11-03): Replace [UTF-8] by
   [RFC2279] for consistency.

   Resolution (2003-11-11): Reference name changed both in text and
   references section to RFC3629 (update of RFC2279).

C.24 A_ED_appendices

   Type: edit

   <http://mailman.webdav.org/pipermail/acl/2003-November/001712.html>

   julian.reschke@greenbytes.de (2003-11-03): Appendices should indeed
   be appendices, not a regular section (see
   draft-rfc-editor-rfc2223bis).

   Resolution (2003-11-04): Moved Section 19.1 to Appendix A and Section
   19.2 to Appendix B.

Index

A
   ACL method  41

C
   Condition Names
      DAV:allowed-principal (pre)  43
      DAV:deny-before-grant (pre)  43
      DAV:grant-only (pre)  43
      DAV:limited-number-of-aces (pre)  43
      DAV:missing-required-principal (pre)  43
      DAV:no-abstract (pre)  43
      DAV:no-ace-conflict (pre)  42
      DAV:no-inherited-ace-conflict (pre)  42
      DAV:no-invert (pre)  43
      DAV:no-protected-ace-conflict (pre)  42
      DAV:not-supported-privilege (pre)  43
      DAV:number-of-matches-within-limits (post)  50, 55
      DAV:recognized-principal (pre)  43

D
   DAV header
      compliance class 'access-control'  40
   DAV:acl property  24
   DAV:acl-principal-prop-set report  49
   DAV:acl-restrictions property  28
   DAV:all privilege ANY>
         <!ELEMENT abstract EMPTY>
         <!ELEMENT description #PCDATA>

         <!--  13
   DAV:allowed-principal precondition  43
   DAV:alternate-URI-set property  14
   DAV:bind privilege  13
   DAV:current-user-privilege-set Property (Section 5.3) -->

         <!ELEMENT current-user-privilege-set (privilege*)>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 56] 
         <!-- DAV:acl Property (Section 5.4) -->

         <!ELEMENT acl (ace)* >
         <!ELEMENT ace ((principal | invert), (grant|deny), protected?,
         inherited?)>

         <!ELEMENT principal (href)
          | all | authenticated | unauthenticated
          | property | self)>

         <!ELEMENT all EMPTY>
         <!ELEMENT authenticated EMPTY>
         <!ELEMENT unauthenticated EMPTY>
         <!ELEMENT  22
   DAV:deny-before-grant precondition  43
   DAV:grant-only precondition  43
   DAV:group property ANY>
         <!ELEMENT self EMPTY>

         <!ELEMENT invert principal>

         <!ELEMENT grant (privilege+)>
         <!ELEMENT deny (privilege+)>
         <!ELEMENT  18
   DAV:group-member-set property  15
   DAV:group-membership property  15
   DAV:inherited-acl-set property  31
   DAV:limited-number-of-aces precondition  43
   DAV:missing-required-principal precondition  43
   DAV:no-abstract precondition  43
   DAV:no-ace-conflict precondition  42
   DAV:no-inherited-ace-conflict precondition  42
   DAV:no-invert precondition  43
   DAV:no-protected-ace-conflict precondition  42
   DAV:not-supported-privilege precondition  43
   DAV:number-of-matches-within-limits postcondition  50, 55
   DAV:owner property  16
   DAV:principal resource type  14
   DAV:principal-collection-set property  31
   DAV:principal-match report  51
   DAV:principal-property-search  53
   DAV:principal-search-property-set  58
   DAV:principal-URL property  15
   DAV:read privilege ANY>

         <!ELEMENT protected EMPTY>

         <!ELEMENT inherited (href)>

         <!--  10
   DAV:read-acl privilege  12
   DAV:read-current-user-privilege-set privilege  12
   DAV:recognized-principal precondition  43
   DAV:supported-privilege-set property  19
   DAV:unbind privilege  13
   DAV:unlock privilege  12
   DAV:write privilege  11
   DAV:write-acl privilege  13
   DAV:write-content privilege  11
   DAV:write-properties privilege  11

M
   Methods
      ACL  41

P
   Privileges
      DAV:all  13
      DAV:bind  13
      DAV:read  10
      DAV:read-acl  12
      DAV:read-current-user-privilege-set  12
      DAV:unbind  13
      DAV:unlock  12
      DAV:write  11
      DAV:write-acl  13
      DAV:write-content  11
      DAV:write-properties  11
   Properties
      DAV:acl  24
      DAV:acl-restrictions Property (Section 5.5) -->

         <!ELEMENT acl-restrictions (grant-only?, no-invert?,
         deny-before-grant?, required-principal?)>

         <!ELEMENT grant-only EMPTY>
         <!ELEMENT no-invert EMPTY>
         <!ELEMENT deny-before-grant EMPTY>

         <!ELEMENT required-principal
           (all? | authenticated? | unauthenticated? | self? | href*
         |property*)>

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 57] 
         <!--  28
      DAV:alternate-URI-set  14
      DAV:current-user-privilege-set  22
      DAV:group  18
      DAV:group-member-set  15
      DAV:group-membership  15
      DAV:inherited-acl-set Property (Section 5.6) -->

         <!ELEMENT inherited-acl-set (href*)>

         <!--  31
      DAV:owner  16
      DAV:principal-collection-set  31
      DAV:principal-URL  15
      DAV:supported-privilege-set  19

R
   Reports
      DAV:acl-principal-prop-set  49
      DAV:principal-match  51
      DAV:principal-property-search  53
      DAV:principal-search-property-set  58
   Resource Types
      DAV:principal  14

Intellectual Property (Section 5.6) -->

         <!ELEMENT principal-collection-set (href*)>

         <!-- Access Control Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights. Information on the
   IETF's procedures with respect to rights in standards-track and Existing Methods (Section 7) -->

         <!ELEMENT need-privileges (resource)* >
         <!ELEMENT resource ( href, privilege )

         <!-- ACL method preconditions (Section 8.1.1) -->

         <!ELEMENT no-ace-conflict EMPTY>
         <!ELEMENT no-protected-ace-conflict EMPTY>
         <!ELEMENT no-inherited-ace-conflict EMPTY>
         <!ELEMENT limited-number-of-aces EMPTY>
         <!ELEMENT grant-only EMPTY>
         <!ELEMENT no-invert EMPTY>
         <!ELEMENT deny-before-grant EMPTY>
         <!ELEMENT no-abstract EMPTY>
         <!ELEMENT not-supported-privilege EMPTY>
         <!ELEMENT missing-required-principal EMPTY>
         <!ELEMENT recognized-principal EMPTY>
         <!ELEMENT allowed-principal EMPTY>

         <!-- REPORTs (Section 9) -->

         <!ELEMENT acl-principal-prop-set ANY>
         ANY value: a sequence
   standards-related documentation can be found in BCP-11. Copies of one
   claims of rights made available for publication and any assurances of
   licenses to be made available, or more elements, with at most one
         DAV:prop element.

         <!ELEMENT principal-match ((principal-property | self), prop?)>
         <!ELEMENT principal-property ANY>
         ANY value: an element whose value identifies a property. The
         expectation is the value result of the named property typically contains an href element that contains attempt made to
   obtain a general license or permission for the URI use of a principal
         <!ELEMENT self EMPTY>

         <!ELEMENT principal-property-search ((property-search+), prop?) >
         <!ELEMENT property-search (prop, match) >
         <!ELEMENT match #PCDATA >

         <!ELEMENT principal-search-property-set (principal-search-
         property*) >
         <!ELEMENT principal-search-property (prop, description) >
         <!ELEMENT description #PCDATA >

    19.2 WebDAV Method Privilege Table (Normative)

    The following table such
   proprietary rights by implementors or users of WebDAV methods (as defined in RFC 2518, 2616,
    and 3253) clarifies which privileges are required for access for each
    method.  Note that this specification can
   be obtained from the privileges listed, if denied, MUST cause access IETF Secretariat.

   The IETF invites any interested party to be denied.  However, given bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that a specific implementation MAY define
    an additional custom privilege may be required to control access practice
   this standard. Please address the information to existing methods,
    having all of the indicated privileges does not mean IETF Executive
   Director.

Full Copyright Statement

   Copyright (C) The Internet Society (2003). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that access will

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 58] comment on or otherwise explain it
   or assist in its implementation may be granted.  Note prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that lack of the indicated privileges does above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
   document itself may not imply
    that access will be denied, since a particular implementation may use a
    sub-privilege aggregated under modified in any way, such as by removing
   the indicated privilege to control
    access.  Privileges required refer copyright notice or references to the current resource being
    processed unless otherwise specified.

    METHOD              PRIVILEGES
     GET                <D:read>
     HEAD               <D:read>
     OPTIONS            <D:read>
     PUT (target exists)     <D:write-content> on target resource
     PUT (no target exists)  <D:bind> on parent collection Internet Society or other
   Internet organizations, except as needed for the purpose of target
     PROPPATCH          <D:write-properties>
     ACL                <D:write-acl>
     PROPFIND           <D:read> (plus <D:read-acl> and
                        <D:read-current-user-privilege-set>
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as needed)
     COPY (target exists)    <D:read>, <D:write-content> and <D:write-
    properties> on target resource
     COPY (no target exists) <D:read>, <D:bind> on target collection
     MOVE (no target exists) <D:unbind> on source collection required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and <D:bind>
    on target collection
     MOVE (target exists)    As above, plus <D:unbind> on will not be
   revoked by the target
    collection
     DELETE             <D:unbind> on parent collection
     LOCK (target exists)    <D:write-content>
     LOCK (no target exists) <D:bind> on parent collection
     MKCOL              <D:bind> on parent collection
     UNLOCK             <D:unlock>
     CHECKOUT           <D:write-properties >
     CHECKIN            <D:write-properties >
     REPORT             <D:read> (on all referenced resources)
     VERSION-CONTROL    <D:write-properties>
     MERGE              <D:write-content>
     MKWORKSPACE        <D:write-content> on parent collection
     BASELINE-CONTROL   <D:write-properties> Internet Society or its successors or assignees.

   This document and <D:write-content>
     MKACTIVITY         <D:write-content> the information contained herein is provided on parent collection

    Clemm, Hopkins, Sedlar, Whitehead                                [Page 59] an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.