--- 1/draft-ietf-iri-3987bis-06.txt 2011-08-14 07:17:23.000000000 +0200 +++ 2/draft-ietf-iri-3987bis-07.txt 2011-08-14 07:17:23.000000000 +0200 @@ -1,21 +1,21 @@ Internationalized Resource Identifiers M. Duerst (iri) Aoyama Gakuin University Internet-Draft M. Suignard Obsoletes: 3987 (if approved) Unicode Consortium Intended status: Standards Track L. Masinter -Expires: February 13, 2012 Adobe - August 12, 2011 +Expires: February 15, 2012 Adobe + August 14, 2011 Internationalized Resource Identifiers (IRIs) - draft-ietf-iri-3987bis-06 + draft-ietf-iri-3987bis-07 Abstract This document defines the Internationalized Resource Identifier (IRI) protocol element, as an extension of the Uniform Resource Identifier (URI). An IRI is a sequence of characters from the Universal Character Set (Unicode/ISO 10646). Grammar and processing rules are given for IRIs and related syntactic forms. In addition, this document provides named additional rule sets for @@ -28,30 +28,31 @@ extending the definition of URI) allows independent orderly transitions: other protocols and languages that use URIs must explicitly choose to allow IRIs. Guidelines are provided for the use and deployment of IRIs and related protocol elements when revising protocols, formats, and software components that currently deal only with URIs. RFC Editor: Please remove the next paragraph before publication. - This document is intended to update RFC 3987 and move towards IETF - Draft Standard. For discussion and comments on this draft, please - join the IETF IRI WG by subscribing to the mailing list - public-iri@w3.org. For a list of open issues, please see the issue - tracker of the WG at http://trac.tools.ietf.org/wg/iri/trac/report/1. - For a list of individual edits, please see the change history at + This (and several companion documents) are intended to obsolete RFC + 3987, and also move towards IETF Draft Standard. For discussion and + comments on these drafts, please join the IETF IRI WG by subscribing + to the mailing list public-iri@w3.org, archives at + http://lists.w3.org/archives/public/public-iri/. For a list of open + issues, please see the issue tracker of the WG at + http://trac.tools.ietf.org/wg/iri/trac/report/1. For a list of + individual edits, please see the change history at http://trac.tools.ietf.org/wg/iri/trac/log/draft-ietf-iri-3987bis. Status of this Memo - This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any @@ -51,21 +52,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on February 13, 2012. + This Internet-Draft will expire on February 15, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -86,86 +87,82 @@ not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1. Overview and Motivation . . . . . . . . . . . . . . . . . 5 1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 6 1.3. Definitions . . . . . . . . . . . . . . . . . . . . . . . 7 - 1.4. Notation . . . . . . . . . . . . . . . . . . . . . . . . 9 + 1.4. Notation . . . . . . . . . . . . . . . . . . . . . . . . 8 2. IRI Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 2.1. Summary of IRI Syntax . . . . . . . . . . . . . . . . . . 10 + 2.1. Summary of IRI Syntax . . . . . . . . . . . . . . . . . . 9 2.2. ABNF for IRI References and IRIs . . . . . . . . . . . . 10 - 3. Processing IRIs and related protocol elements . . . . . . . . 13 - 3.1. Converting to UCS . . . . . . . . . . . . . . . . . . . . 14 - 3.2. Parse the IRI into IRI components . . . . . . . . . . . . 14 - 3.3. General percent-encoding of IRI components . . . . . . . 15 - 3.4. Mapping ireg-name . . . . . . . . . . . . . . . . . . . . 15 - 3.4.1. Mapping using Percent-Encoding . . . . . . . . . . . . 15 - 3.4.2. Mapping using Punycode . . . . . . . . . . . . . . . . 16 - 3.4.3. Additional Considerations . . . . . . . . . . . . . . 16 - 3.5. Mapping query components . . . . . . . . . . . . . . . . 17 - 3.6. Mapping IRIs to URIs . . . . . . . . . . . . . . . . . . 17 - 3.7. Converting URIs to IRIs . . . . . . . . . . . . . . . . . 17 - 3.7.1. Examples . . . . . . . . . . . . . . . . . . . . . . . 19 - 4. Bidirectional IRIs for Right-to-Left Languages . . . . . . . . 20 - 4.1. Logical Storage and Visual Presentation . . . . . . . . . 21 - 4.2. Bidi IRI Structure . . . . . . . . . . . . . . . . . . . 22 - 4.3. Input of Bidi IRIs . . . . . . . . . . . . . . . . . . . 23 - 4.4. Examples . . . . . . . . . . . . . . . . . . . . . . . . 23 - 5. Use of IRIs . . . . . . . . . . . . . . . . . . . . . . . . . 25 - 5.1. Limitations on UCS Characters Allowed in IRIs . . . . . . 25 - 5.2. Software Interfaces and Protocols . . . . . . . . . . . . 26 - 5.3. Format of URIs and IRIs in Documents and Protocols . . . 26 - 5.4. Use of UTF-8 for Encoding Original Characters . . . . . . 26 - 5.5. Relative IRI References . . . . . . . . . . . . . . . . . 28 - 6. Liberal Handling of Otherwise Invalid IRIs . . . . . . . . . . 28 - 6.1. LEIRI Processing . . . . . . . . . . . . . . . . . . . . 29 - 6.2. Web Address Processing . . . . . . . . . . . . . . . . . 29 - 6.3. Characters Not Allowed in IRIs . . . . . . . . . . . . . 31 - 7. URI/IRI Processing Guidelines (Informative) . . . . . . . . . 33 - 7.1. URI/IRI Software Interfaces . . . . . . . . . . . . . . . 33 - 7.2. URI/IRI Entry . . . . . . . . . . . . . . . . . . . . . . 33 - 7.3. URI/IRI Transfer between Applications . . . . . . . . . . 34 - 7.4. URI/IRI Generation . . . . . . . . . . . . . . . . . . . 34 - 7.5. URI/IRI Selection . . . . . . . . . . . . . . . . . . . . 35 - 7.6. Display of URIs/IRIs . . . . . . . . . . . . . . . . . . 36 - 7.7. Interpretation of URIs and IRIs . . . . . . . . . . . . . 36 - 7.8. Upgrading Strategy . . . . . . . . . . . . . . . . . . . 37 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 - 9. Security Considerations . . . . . . . . . . . . . . . . . . . 38 - 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 39 - 11. Main Changes Since RFC 3987 . . . . . . . . . . . . . . . . . 40 - 11.1. Major restructuring of IRI processing model . . . . . . . 40 - 11.1.1. OLD WAY . . . . . . . . . . . . . . . . . . . . . . . 40 - 11.1.2. NEW WAY . . . . . . . . . . . . . . . . . . . . . . . 40 - 11.1.3. Extension of Syntax . . . . . . . . . . . . . . . . . 41 - 11.1.4. More to be added . . . . . . . . . . . . . . . . . . . 41 - 11.2. Change Log . . . . . . . . . . . . . . . . . . . . . . . 41 - 11.2.1. Changes after draft-ietf-iri-3987bis-01 . . . . . . . 41 - 11.2.2. Changes from draft-duerst-iri-bis-07 to - draft-ietf-iri-3987bis-00 . . . . . . . . . . . . . . 41 - 11.2.3. Changes from -06 to -07 of draft-duerst-iri-bis . . . 41 - 11.3. Changes from -00 to -01 . . . . . . . . . . . . . . . . . 41 - 11.4. Changes from -05 to -06 of draft-duerst-iri-bis-00 . . . 42 - 11.5. Changes from -04 to -05 of draft-duerst-iri-bis . . . . . 42 - 11.6. Changes from -03 to -04 of draft-duerst-iri-bis . . . . . 42 - 11.7. Changes from -02 to -03 of draft-duerst-iri-bis . . . . . 42 - 11.8. Changes from -01 to -02 of draft-duerst-iri-bis . . . . . 42 - 11.9. Changes from -00 to -01 of draft-duerst-iri-bis . . . . . 42 - 11.10. Changes from RFC 3987 to -00 of draft-duerst-iri-bis . . 43 - 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43 - 12.1. Normative References . . . . . . . . . . . . . . . . . . 43 - 12.2. Informative References . . . . . . . . . . . . . . . . . 44 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 46 + 3. Processing IRIs and related protocol elements . . . . . . . . 12 + 3.1. Converting to UCS . . . . . . . . . . . . . . . . . . . . 13 + 3.2. Parse the IRI into IRI components . . . . . . . . . . . . 13 + 3.3. General percent-encoding of IRI components . . . . . . . 14 + 3.4. Mapping ireg-name . . . . . . . . . . . . . . . . . . . . 14 + 3.4.1. Mapping using Percent-Encoding . . . . . . . . . . . . 14 + 3.4.2. Mapping using Punycode . . . . . . . . . . . . . . . . 14 + 3.4.3. Additional Considerations . . . . . . . . . . . . . . 15 + 3.5. Mapping query components . . . . . . . . . . . . . . . . 16 + 3.6. Mapping IRIs to URIs . . . . . . . . . . . . . . . . . . 16 + 3.7. Converting URIs to IRIs . . . . . . . . . . . . . . . . . 16 + 3.7.1. Examples . . . . . . . . . . . . . . . . . . . . . . . 18 + 4. Use of IRIs . . . . . . . . . . . . . . . . . . . . . . . . . 19 + 4.1. Limitations on UCS Characters Allowed in IRIs . . . . . . 19 + 4.2. Software Interfaces and Protocols . . . . . . . . . . . . 20 + 4.3. Format of URIs and IRIs in Documents and Protocols . . . 20 + 4.4. Use of UTF-8 for Encoding Original Characters . . . . . . 20 + 4.5. Relative IRI References . . . . . . . . . . . . . . . . . 22 + 5. Liberal Handling of Otherwise Invalid IRIs . . . . . . . . . . 22 + 5.1. LEIRI Processing . . . . . . . . . . . . . . . . . . . . 22 + 6. Characters Not Allowed in IRIs . . . . . . . . . . . . . . . . 23 + 7. URI/IRI Processing Guidelines (Informative) . . . . . . . . . 25 + 7.1. URI/IRI Software Interfaces . . . . . . . . . . . . . . . 25 + 7.2. URI/IRI Entry . . . . . . . . . . . . . . . . . . . . . . 25 + 7.3. URI/IRI Transfer between Applications . . . . . . . . . . 26 + 7.4. URI/IRI Generation . . . . . . . . . . . . . . . . . . . 27 + 7.5. URI/IRI Selection . . . . . . . . . . . . . . . . . . . . 27 + 7.6. Display of URIs/IRIs . . . . . . . . . . . . . . . . . . 28 + 7.7. Interpretation of URIs and IRIs . . . . . . . . . . . . . 28 + 7.8. Upgrading Strategy . . . . . . . . . . . . . . . . . . . 29 + 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 + 9. Security Considerations . . . . . . . . . . . . . . . . . . . 30 + 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 31 + 11. Main Changes Since RFC 3987 . . . . . . . . . . . . . . . . . 32 + 11.1. Split out Bidi, processing guidelines, comparison + sections . . . . . . . . . . . . . . . . . . . . . . . . 32 + 11.2. Major restructuring of IRI processing model . . . . . . . 32 + 11.2.1. OLD WAY . . . . . . . . . . . . . . . . . . . . . . . 32 + 11.2.2. NEW WAY . . . . . . . . . . . . . . . . . . . . . . . 32 + 11.2.3. Extension of Syntax . . . . . . . . . . . . . . . . . 33 + 11.2.4. More to be added . . . . . . . . . . . . . . . . . . . 33 + 11.3. Change Log . . . . . . . . . . . . . . . . . . . . . . . 33 + 11.3.1. Changes after draft-ietf-iri-3987bis-01 . . . . . . . 33 + 11.3.2. Changes from draft-duerst-iri-bis-07 to + draft-ietf-iri-3987bis-00 . . . . . . . . . . . . . . 33 + 11.3.3. Changes from -06 to -07 of draft-duerst-iri-bis . . . 33 + 11.4. Changes from -00 to -01 . . . . . . . . . . . . . . . . . 33 + 11.5. Changes from -05 to -06 of draft-duerst-iri-bis-00 . . . 34 + 11.6. Changes from -04 to -05 of draft-duerst-iri-bis . . . . . 34 + 11.7. Changes from -03 to -04 of draft-duerst-iri-bis . . . . . 34 + 11.8. Changes from -02 to -03 of draft-duerst-iri-bis . . . . . 34 + 11.9. Changes from -01 to -02 of draft-duerst-iri-bis . . . . . 34 + 11.10. Changes from -00 to -01 of draft-duerst-iri-bis . . . . . 34 + 11.11. Changes from RFC 3987 to -00 of draft-duerst-iri-bis . . 35 + 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35 + 12.1. Normative References . . . . . . . . . . . . . . . . . . 35 + 12.2. Informative References . . . . . . . . . . . . . . . . . 36 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 1. Introduction 1.1. Overview and Motivation A Uniform Resource Identifier (URI) is defined in [RFC3986] as a sequence of characters chosen from a limited subset of the repertoire of US-ASCII [ASCII] characters. The characters in URIs are frequently used for representing words of @@ -194,43 +191,48 @@ [RFC3986]. This document defines the protocol element called Internationalized Resource Identifier (IRI), which allow applications of URIs to be extended to use resource identifiers that have a much wider repertoire of characters. It also provides corresponding "internationalized" versions of other constructs from [RFC3986], such as URI references. The syntax of IRIs is defined in Section 2. Using characters outside of A - Z in IRIs adds a number of - difficulties. Section 4 discusses the special case of bidirectional - IRIs using characters from scripts written right-to-left. Section 5 - discusses the use of IRIs in different situations. Section 7 gives - additional informative guidelines. Section 9 discusses IRI-specific - security considerations. + difficulties. Section 4 discusses the use of IRIs in different + situations. Section 7 gives additional informative guidelines. + Section 9 discusses IRI-specific security considerations. + + [Bidi] discusses the special case of bidirectional IRIs using + characters from scripts written right-to-left. [Equivalence] gives + guidelines for applications wishing to determine if two IRIs are + equivalent, as well as defining some equivalence methods. + [RFC4395bis] updates the URI scheme registration guidelines and + proceedures to note that every URI scheme is also automatically an + IRI scheme and to allow scheme definitions to be directly described + in terms of Unicode characters. When originally defining IRIs, several design alternatives were considered. Historically interested readers can find an overview in Appendix A of [RFC3987]. For some additional background on the design of URIs and IRIs, please also see [Gettys]. 1.2. Applicability IRIs are designed to allow protocols and software that deal with URIs - to be updated to handle IRIs. A "URI scheme" (as defined by - [RFC3986] and registered through the IANA process defined in - [RFC4395bis] also serves as an "IRI scheme". Processing of IRIs is - accomplished by extending the URI syntax while retaining (and not - expanding) the set of "reserved" characters, such that the syntax for - any URI scheme may be extended to allow non-ASCII characters. In - addition, following parsing of an IRI, it is possible to construct a - corresponding URI by first encoding characters outside of the allowed - URI range and then reassembling the components. + to be updated to handle IRIs. Processing of IRIs is accomplished by + extending the URI syntax while retaining (and not expanding) the set + of "reserved" characters, such that the syntax for any URI scheme may + be extended to allow non-ASCII characters. In addition, following + parsing of an IRI, it is possible to construct a corresponding URI by + first encoding characters outside of the allowed URI range and then + reassembling the components. Practical use of IRIs forms in place of URIs forms depends on the following conditions being met: a. A protocol or format element MUST be explicitly designated to be able to carry IRIs. The intent is to avoid introducing IRIs into contexts that are not defined to accept them. For example, XML schema [XMLSchema] has an explicit type "anyURI" that includes IRIs and IRI references. Therefore, IRIs and IRI references can be in attributes and elements of type "anyURI". On the other @@ -246,21 +248,21 @@ c. The URI scheme definition, if it explicitly allows a percent sign ("%") in any syntactic component, SHOULD define the interpretation of sequences of percent-encoded octets (using "%XX" hex octets) as octet from sequences of UTF-8 encoded strings; this is recommended in the guidelines for registering new schemes, [RFC4395bis]. For example, this is the practice for IMAP URLs [RFC2192], POP URLs [RFC2384] and the URN syntax [RFC2141]). Note that use of percent-encoding may also be restricted in some situations, for example, URI schemes that disallow percent-encoding might still be used with a fragment identifier which is percent-encoded (e.g., - [XPointer]). See Section 5.4 for further discussion. + [XPointer]). See Section 4.4 for further discussion. 1.3. Definitions The following definitions are used in this document; they follow the terms in [RFC2130], [RFC2277], and [ISO10646]. character: A member of a set of elements used for the organization, control, or representation of data. For example, "LATIN CAPITAL LETTER A" names a character. @@ -286,39 +288,24 @@ ISO/IEC 10646 [ISO10646] and the Unicode Standard [UNIV6]. IRI reference: Denotes the common usage of an Internationalized Resource Identifier. An IRI reference may be absolute or relative. However, the "IRI" that results from such a reference only includes absolute IRIs; any relative IRI references are resolved to their absolute form. Note that in [RFC2396] URIs did not include fragment identifiers, but in [RFC3986] fragment identifiers are part of URIs. - URL: The term "URL" was originally used [RFC1738] for roughly what - is now called a "URI". Books, software and documentation often - refers to URIs and IRIs using the "URL" term. Some usages - restrict "URL" to those URIs which are not URNs. Because of the - ambiguity of the term using the term "URL" is NOT RECOMMENDED in - formal documents. - LEIRI (Legacy Extended IRI) processing: This term was used in various XML specifications to refer to strings that, although not valid IRIs, were acceptable input to the processing rules in - Section 6.1. - - (Web Address, Hypertext Reference, HREF): These terms have been - added in this document for convenience, to allow other - specifications to refer to those strings that, although not valid - IRIs, are acceptable input to the processing rules in Section 6.2. - This usage corresponds to the parsing rules of some popular web - browsing applications. ISSUE: Need to find a good name/ - abbreviation for these. + Section 5.1. running text: Human text (paragraphs, sentences, phrases) with syntax according to orthographic conventions of a natural language, as opposed to syntax defined for ease of processing by machines (e.g., markup, programming languages). protocol element: Any portion of a message that affects processing of that message by the protocol in question. presentation element: A presentation form corresponding to a @@ -353,32 +340,27 @@ 1.4. Notation RFCs and Internet Drafts currently do not allow any characters outside the US-ASCII repertoire. Therefore, this document uses various special notations to denote such characters in examples. In text, characters outside US-ASCII are sometimes referenced by using a prefix of 'U+', followed by four to six hexadecimal digits. To represent characters outside US-ASCII in examples, this document - uses two notations: 'XML Notation' and 'Bidi Notation'. + uses 'XML Notation'. XML Notation uses a leading '&#x', a trailing ';', and the hexadecimal number of the character in the UCS in between. For example, я stands for CYRILLIC CAPITAL LETTER YA. In this notation, an actual '&' is denoted by '&'. - Bidi Notation is used for bidirectional examples: Lower case letters - stand for Latin letters or other letters that are written left to - right, whereas upper case letters represent Arabic or Hebrew letters - that are written right to left. - To denote actual octets in examples (as opposed to percent-encoded octets), the two hex digits denoting the octet are enclosed in "<" and ">". For example, the octet often denoted as 0xc9 is denoted here as . In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in [RFC2119]. 2. IRI Syntax @@ -396,21 +378,21 @@ the containing protocol or document ensures that the characters in the IRI can be handled (e.g., searched, converted, displayed) in the same way as the rest of the protocol or document. 2.1. Summary of IRI Syntax The IRI syntax extends the URI syntax in [RFC3986] by extending the class of unreserved characters, primarily by adding the characters of the UCS (Universal Character Set, [ISO10646]) beyond U+007F, subject to the limitations given in the syntax rules below and in - Section 5.1. + Section 4.1. The syntax and use of components and reserved characters is the same as that in [RFC3986]. Each "URI scheme" thus also functions as an "IRI scheme", in that scheme-specific parsing rules for URIs of a scheme are be extended to allow parsing of IRIs using the same parsing rules. All the operations defined in [RFC3986], such as the resolution of relative references, can be applied to IRIs by IRI-processing software in exactly the same way as they are for URIs by URI- @@ -596,43 +578,20 @@ represented independent of any character encoding) represent the IRI as a sequence of characters from the UCS normalized according to Unicode Normalization Form C (NFC, [UTR15]). 3.2. Parse the IRI into IRI components Parse the IRI, either as a relative reference (no scheme) or using scheme specific processing (according to the scheme given); the result is a set of parsed IRI components. - NOTE: The result of parsing into components will correspond to - subtrings of the IRI that may be accessible via an API. For example, - in [HTML5], the protocol components of interest are SCHEME (scheme), - HOST (ireg-name), PORT (port), the PATH (ipath after the initial - "/"), QUERY (iquery), FRAGMENT (ifragment), and AUTHORITY - (iauthority). - - Subsequent processing rules are sometimes used to define other - syntactic components. For example, [HTML5] defines APIs for IRI - processing; in these APIs: - - HOSTSPECIFIC the substring that follows the substring matched by the - iauthority production, or the whole string if the iauthority - production wasn't matched. - - HOSTPORT if there is a scheme component and a port component and the - port given by the port component is different than the default - port defined for the protocol given by the scheme component, then - HOSTPORT is the substring that starts with the substring matched - by the host production and ends with the substring matched by the - port production, and includes the colon in between the two. - Otherwise, it is the same as the host component. - 3.3. General percent-encoding of IRI components Except as noted in the following subsections, IRI components are mapped to the equivalent URI components by percent-encoding those characters not allowed in URIs. Previous processing steps will have removed some characters, and the interpretation of reserved characters will have already been done (with the syntactic reserved characters outside of the IRI component). This mapping is defined for all sequences of Unicode characters, whether or not they are valid for the component in question. @@ -715,32 +674,31 @@ when arbitrary content is included in some part of a URI.) For example, an IRI of "http://www.example.org/red%09rosé#red" (in XML notation) is converted to "http://www.example.org/red%09ros%C3%A9#red", not to something like "http%3A%2F%2Fwww.example.org%2Fred%2509ros%C3%A9%23red". 3.5. Mapping query components - ((NOTE: SEE ISSUES LIST)) For compatibility with existing deployed - HTTP infrastructure, the following special case applies for schemes - "http" and "https" and IRIs whose origin has a document charset other - than one which is UCS-based (e.g., UTF-8 or UTF-16). In such a case, - the "query" component of an IRI is mapped into a URI by using the - document charset rather than UTF-8 as the binary representation - before pct-encoding. This mapping is not applied for any other - scheme or component. + For compatibility with existing deployed HTTP infrastructure, the + following special case applies for schemes "http" and "https" and + IRIs whose origin has a document charset other than one which is UCS- + based (e.g., UTF-8 or UTF-16). In such a case, the "query" component + of an IRI is mapped into a URI by using the document charset rather + than UTF-8 as the binary representation before pct-encoding. This + mapping is not applied for any other scheme or component. 3.6. Mapping IRIs to URIs - The canonical mapping from a IRI to URI is defined by applying the + The mapping from an IRI to URI is accomplished by applying the mapping above (from IRI to URI components) and then reassembling a URI from the parsed URI components using the original punctuation that delimited the IRI components. 3.7. Converting URIs to IRIs In some situations, for presentation and further processing, it is desirable to convert a URI into an equivalent IRI in which natural characters are represented directly rather than percent encoded. Of course, every URI is already an IRI in its own right without any @@ -763,53 +721,52 @@ 2. Some percent-encodings cannot be interpreted as sequences of UTF-8 octets. (Note: The octet patterns of UTF-8 are highly regular. Therefore, there is a very high probability, but no guarantee, that percent- encodings that can be interpreted as sequences of UTF-8 octets actually originated from UTF-8. For a detailed discussion, see [Duerst97].) 3. The conversion may result in a character that is not appropriate - in an IRI. See Section 2.2, Section 4.1, and Section 5.1 for - further details. + in an IRI. See Section 2.2, and Section 4.1 for further details. 4. IRI to URI conversion has different rules for dealing with domain names and query parameters. Conversion from a URI to an IRI MAY be done by using the following steps: 1. Represent the URI as a sequence of octets in US-ASCII. 2. Convert all percent-encodings ("%" followed by two hexadecimal digits) to the corresponding octets, except those corresponding to "%", characters in "reserved", and characters in US-ASCII not allowed in URIs. 3. Re-percent-encode any octet produced in step 2 that is not part of a strictly legal UTF-8 octet sequence. 4. Re-percent-encode all octets produced in step 3 that in UTF-8 represent characters that are not appropriate according to - Section 2.2, Section 4.1, and Section 5.1. + Section 2.2 and Section 4.1. 5. Interpret the resulting octet sequence as a sequence of characters encoded in UTF-8. 6. URIs known to contain domain names in the reg-name component SHOULD convert punycode-encoded domain name labels to the corresponding characters using the ToUnicode procedure. This procedure will convert as many percent-encoded characters as possible to characters in an IRI. Because there are some choices - when step 4 is applied (see Section 5.1), results may vary. + when step 4 is applied (see Section 4.1), results may vary. Conversions from URIs to IRIs MUST NOT use any character encoding other than UTF-8 in steps 3 and 4, even if it might be possible to guess from the context that another character encoding than UTF-8 was used in the URI. For example, the URI "http://www.example.org/r%E9sum%E9.html" might with some guessing be interpreted to contain two e-acute characters encoded as iso-8859-1. It must not be converted to an IRI containing these e-acute characters. Otherwise, in the future the IRI will be mapped to "http://www.example.org/r%C3%A9sum%C3%A9.html", which is a different @@ -854,281 +811,52 @@ 3. http://www.example.org/D%FCrst 4. http://www.example.org/D%FCrst 5. http://www.example.org/D%FCrst 6. http://www.example.org/D%FCrst The following example contains "%e2%80%ae", which is the percent- encoded - UTF-8 character encoding of U+202E, RIGHT-TO-LEFT OVERRIDE. - Section 4.1 forbids the direct use of this character in an IRI. - Therefore, the corresponding octets are re-percent-encoded in step 4. - This example shows that the case (upper- or lowercase) of letters - used in percent-encodings may not be preserved. The example also - contains a punycode-encoded domain name label (xn--99zt52a), which is - not converted. + UTF-8 character encoding of U+202E, RIGHT-TO-LEFT OVERRIDE. The + direct use of this character is forbiddin in an IRI. Therefore, the + corresponding octets are re-percent-encoded in step 4. This example + shows that the case (upper- or lowercase) of letters used in percent- + encodings may not be preserved. The example also contains a + punycode-encoded domain name label (xn--99zt52a), which is not + converted. 1. http://xn--99zt52a.example.org/%e2%80%ae 2. http://xn--99zt52a.example.org/<80> 3. http://xn--99zt52a.example.org/<80> 4. http://xn--99zt52a.example.org/%E2%80%AE 5. http://xn--99zt52a.example.org/%E2%80%AE 6. http://納豆.example.org/%E2%80%AE Note that the label "xn--99zt52a" is converted to U+7D0D U+8C46 (Japanese Natto). ((EDITOR NOTE: There is some inconsistency in this note.)) -4. Bidirectional IRIs for Right-to-Left Languages - - Some UCS characters, such as those used in the Arabic and Hebrew - scripts, have an inherent right-to-left (rtl) writing direction. - IRIs containing these characters (called bidirectional IRIs or Bidi - IRIs) require additional attention because of the non-trivial - relation between logical representation (used for digital - representation and for reading/spelling) and visual representation - (used for display/printing). - - Because of the complex interaction between the logical - representation, the visual representation, and the syntax of a Bidi - IRI, a balance is needed between various requirements. The main - requirements are - - 1. user-predictable conversion between visual and logical - representation; - - 2. the ability to include a wide range of characters in various parts - of the IRI; and - - 3. minor or no changes or restrictions for implementations. - -4.1. Logical Storage and Visual Presentation - - When stored or transmitted in digital representation, bidirectional - IRIs MUST be in full logical order and MUST conform to the IRI syntax - rules (which includes the rules relevant to their scheme). This - ensures that bidirectional IRIs can be processed in the same way as - other IRIs. - - Bidirectional IRIs MUST be rendered by using the Unicode - Bidirectional Algorithm [UNIV6], [UNI9]. Bidirectional IRIs MUST be - rendered in the same way as they would be if they were in a left-to- - right embedding; i.e., as if they were preceded by U+202A, LEFT-TO- - RIGHT EMBEDDING (LRE), and followed by U+202C, POP DIRECTIONAL - FORMATTING (PDF). Setting the embedding direction can also be done - in a higher-level protocol (e.g., the dir='ltr' attribute in HTML). - - There is no requirement to use the above embedding if the display is - still the same without the embedding. For example, a bidirectional - IRI in a text with left-to-right base directionality (such as used - for English or Cyrillic) that is preceded and followed by whitespace - and strong left-to-right characters does not need an embedding. - Also, a bidirectional relative IRI reference that only contains - strong right-to-left characters and weak characters and that starts - and ends with a strong right-to-left character and appears in a text - with right-to-left base directionality (such as used for Arabic or - Hebrew) and is preceded and followed by whitespace and strong - characters does not need an embedding. - - In some other cases, using U+200E, LEFT-TO-RIGHT MARK (LRM), may be - sufficient to force the correct display behavior. However, the - details of the Unicode Bidirectional algorithm are not always easy to - understand. Implementers are strongly advised to err on the side of - caution and to use embedding in all cases where they are not - completely sure that the display behavior is unaffected without the - embedding. - - The Unicode Bidirectional Algorithm ([UNI9], section 4.3) permits - higher-level protocols to influence bidirectional rendering. Such - changes by higher-level protocols MUST NOT be used if they change the - rendering of IRIs. - - The bidirectional formatting characters that may be used before or - after the IRI to ensure correct display are not themselves part of - the IRI. IRIs MUST NOT contain bidirectional formatting characters - (LRM, RLM, LRE, RLE, LRO, RLO, and PDF). They affect the visual - rendering of the IRI but do not appear themselves. It would - therefore not be possible to input an IRI with such characters - correctly. - -4.2. Bidi IRI Structure - - The Unicode Bidirectional Algorithm is designed mainly for running - text. To make sure that it does not affect the rendering of - bidirectional IRIs too much, some restrictions on bidirectional IRIs - are necessary. These restrictions are given in terms of delimiters - (structural characters, mostly punctuation such as "@", ".", ":", and - "/") and components (usually consisting mostly of letters and - digits). - - The following syntax rules from Section 2.2 correspond to components - for the purpose of Bidi behavior: iuserinfo, ireg-name, isegment, - isegment-nz, isegment-nz-nc, ireg-name, iquery, and ifragment. - - Specifications that define the syntax of any of the above components - MAY divide them further and define smaller parts to be components - according to this document. As an example, the restrictions of - [RFC3490] on bidirectional domain names correspond to treating each - label of a domain name as a component for schemes with ireg-name as a - domain name. Even where the components are not defined formally, it - may be helpful to think about some syntax in terms of components and - to apply the relevant restrictions. For example, for the usual name/ - value syntax in query parts, it is convenient to treat each name and - each value as a component. As another example, the extensions in a - resource name can be treated as separate components. - - For each component, the following restrictions apply: - - 1. A component SHOULD NOT use both right-to-left and left-to-right - characters. - - 2. A component using right-to-left characters SHOULD start and end - with right-to-left characters. - - The above restrictions are given as "SHOULD"s, rather than as - "MUST"s. For IRIs that are never presented visually, they are not - relevant. However, for IRIs in general, they are very important to - ensure consistent conversion between visual presentation and logical - representation, in both directions. - - Note: In some components, the above restrictions may actually be - strictly enforced. For example, [RFC3490] requires that these - restrictions apply to the labels of a host name for those schemes - where ireg-name is a host name. In some other components (for - example, path components) following these restrictions may not be - too difficult. For other components, such as parts of the query - part, it may be very difficult to enforce the restrictions because - the values of query parameters may be arbitrary character - sequences. - - If the above restrictions cannot be satisfied otherwise, the affected - component can always be mapped to URI notation as described in - Section 3.3. Please note that the whole component has to be mapped - (see also Example 9 below). - -4.3. Input of Bidi IRIs - - Bidi input methods MUST generate Bidi IRIs in logical order while - rendering them according to Section 4.1. During input, rendering - SHOULD be updated after every new character is input to avoid end- - user confusion. - -4.4. Examples - - This section gives examples of bidirectional IRIs, in Bidi Notation. - It shows legal IRIs with the relationship between logical and visual - representation and explains how certain phenomena in this - relationship may look strange to somebody not familiar with - bidirectional behavior, but familiar to users of Arabic and Hebrew. - It also shows what happens if the restrictions given in Section 4.2 - are not followed. The examples below can be seen at [BidiEx], in - Arabic, Hebrew, and Bidi Notation variants. - - To read the bidi text in the examples, read the visual representation - from left to right until you encounter a block of rtl text. Read the - rtl block (including slashes and other special characters) from right - to left, then continue at the next unread ltr character. - - Example 1: A single component with rtl characters is inverted: - Logical representation: "http://ab.CDEFGH.ij/kl/mn/op.html" - Visual representation: "http://ab.HGFEDC.ij/kl/mn/op.html" - Components can be read one by one, and each component can be read in - its natural direction. - - Example 2: More than one consecutive component with rtl characters is - inverted as a whole: - Logical representation: "http://ab.CDE.FGH/ij/kl/mn/op.html" - Visual representation: "http://ab.HGF.EDC/ij/kl/mn/op.html" - A sequence of rtl components is read rtl, in the same way as a - sequence of rtl words is read rtl in a bidi text. - - Example 3: All components of an IRI (except for the scheme) are rtl. - All rtl components are inverted overall: - Logical representation: "http://AB.CD.EF/GH/IJ/KL?MN=OP;QR=ST#UV" - Visual representation: "http://VU#TS=RQ;PO=NM?LK/JI/HG/FE.DC.BA" - The whole IRI (except the scheme) is read rtl. Delimiters between - rtl components stay between the respective components; delimiters - between ltr and rtl components don't move. - - Example 4: Each of several sequences of rtl components is inverted on - its own: - Logical representation: "http://AB.CD.ef/gh/IJ/KL.html" - Visual representation: "http://DC.BA.ef/gh/LK/JI.html" - Each sequence of rtl components is read rtl, in the same way as each - sequence of rtl words in an ltr text is read rtl. - - Example 5: Example 2, applied to components of different kinds: - Logical representation: "http://ab.cd.EF/GH/ij/kl.html" - Visual representation: "http://ab.cd.HG/FE/ij/kl.html" - The inversion of the domain name label and the path component may be - unexpected, but it is consistent with other bidi behavior. For - reassurance that the domain component really is "ab.cd.EF", it may be - helpful to read aloud the visual representation following the bidi - algorithm. After "http://ab.cd." one reads the RTL block - "E-F-slash-G-H", which corresponds to the logical representation. - - Example 6: Same as Example 5, with more rtl components: - Logical representation: "http://ab.CD.EF/GH/IJ/kl.html" - Visual representation: "http://ab.JI/HG/FE.DC/kl.html" - The inversion of the domain name labels and the path components may - be easier to identify because the delimiters also move. - - Example 7: A single rtl component includes digits: - Logical representation: "http://ab.CDE123FGH.ij/kl/mn/op.html" - Visual representation: "http://ab.HGF123EDC.ij/kl/mn/op.html" - Numbers are written ltr in all cases but are treated as an additional - embedding inside a run of rtl characters. This is completely - consistent with usual bidirectional text. - - Example 8 (not allowed): Numbers are at the start or end of an rtl - component: - Logical representation: "http://ab.cd.ef/GH1/2IJ/KL.html" - Visual representation: "http://ab.cd.ef/LK/JI1/2HG.html" - The sequence "1/2" is interpreted by the bidi algorithm as a - fraction, fragmenting the components and leading to confusion. There - are other characters that are interpreted in a special way close to - numbers; in particular, "+", "-", "#", "$", "%", ",", ".", and ":". - - Example 9 (not allowed): The numbers in the previous example are - percent-encoded: - Logical representation: "http://ab.cd.ef/GH%31/%32IJ/KL.html", - Visual representation: "http://ab.cd.ef/LK/JI%32/%31HG.html" - - Example 10 (allowed but not recommended): - Logical representation: "http://ab.CDEFGH.123/kl/mn/op.html" - Visual representation: "http://ab.123.HGFEDC/kl/mn/op.html" - Components consisting of only numbers are allowed (it would be rather - difficult to prohibit them), but these may interact with adjacent RTL - components in ways that are not easy to predict. - - Example 11 (allowed but not recommended): - Logical representation: "http://ab.CDEFGH.123ij/kl/mn/op.html" - Visual representation: "http://ab.123.HGFEDCij/kl/mn/op.html" - Components consisting of numbers and left-to-right characters are - allowed, but these may interact with adjacent RTL components in ways - that are not easy to predict. - -5. Use of IRIs +4. Use of IRIs -5.1. Limitations on UCS Characters Allowed in IRIs +4.1. Limitations on UCS Characters Allowed in IRIs This section discusses limitations on characters and character - sequences usable for IRIs beyond those given in Section 2.2 and - Section 4.1. The considerations in this section are relevant when - IRIs are created and when URIs are converted to IRIs. + sequences usable for IRIs beyond those given in Section 2.2. The + considerations in this section are relevant when IRIs are created and + when URIs are converted to IRIs. a. The repertoire of characters allowed in each IRI component is limited by the definition of that component. For example, the definition of the scheme component does not allow characters beyond US-ASCII. (Note: In accordance with URI practice, generic IRI software cannot and should not check for such limitations.) b. The UCS contains many areas of characters for which there are @@ -1137,34 +865,34 @@ the full-width equivalents of Latin characters, half-width Katakana characters for Japanese, and many others. It also includes many look-alikes of "space", "delims", and "unwise", characters excluded in [RFC3491]. Additional information is available from [UNIXML]. [UNIXML] is written in the context of running text rather than in that of identifiers. Nevertheless, it discusses many of the categories of characters not appropriate for IRIs. -5.2. Software Interfaces and Protocols +4.2. Software Interfaces and Protocols Although an IRI is defined as a sequence of characters, software interfaces for URIs typically function on sequences of octets or other kinds of code units. Thus, software interfaces and protocols MUST define which character encoding is used. Intermediate software interfaces between IRI-capable components and URI-only components MUST map the IRIs per Section 3.6, when transferring from IRI-capable to URI-only components. This mapping SHOULD be applied as late as possible. It SHOULD NOT be applied between components that are known to be able to handle IRIs. -5.3. Format of URIs and IRIs in Documents and Protocols +4.3. Format of URIs and IRIs in Documents and Protocols Document formats that transport URIs may have to be upgraded to allow the transport of IRIs. In cases where the document as a whole has a native character encoding, IRIs MUST also be encoded in this character encoding and converted accordingly by a parser or interpreter. IRI characters not expressible in the native character encoding SHOULD be escaped by using the escaping conventions of the document format if such conventions are available. Alternatively, they MAY be percent-encoded according to Section 3.6. For example, in HTML or XML, numeric character references SHOULD be used. If a @@ -1173,21 +901,21 @@ the document in the UTF-8 character encoding. ((UPDATE THIS NOTE)) Note: Some formats already accommodate IRIs, although they use different terminology. HTML 4.0 [HTML4] defines the conversion from IRIs to URIs as error-avoiding behavior. XML 1.0 [XML1], XLink [XLink], XML Schema [XMLSchema], and specifications based upon them allow IRIs. Also, it is expected that all relevant new W3C formats and protocols will be required to handle IRIs [CharMod]. -5.4. Use of UTF-8 for Encoding Original Characters +4.4. Use of UTF-8 for Encoding Original Characters This section discusses details and gives examples for point c) in Section 1.2. To be able to use IRIs, the URI corresponding to the IRI in question has to encode original characters into octets by using UTF-8. This can be specified for all URIs of a URI scheme or can apply to individual URIs for schemes that do not specify how to encode original characters. It can apply to the whole URI, or only to some part. For background information on encoding characters into URIs, see also Section 2.5 of [RFC3986]. @@ -1251,147 +979,61 @@ document name is encoded in iso-8859-1 based on server settings, but where the fragment identifier is encoded in UTF-8 according to [XPointer]. The IRI corresponding to the above URI would be (in XML notation) "http://www.example.org/r%E9sum%E9.xml#résumé". Similar considerations apply to query parts. The functionality of IRIs (namely, to be able to include non-ASCII characters) can only be used if the query part is encoded in UTF-8. -5.5. Relative IRI References +4.5. Relative IRI References Processing of relative IRI references against a base is handled straightforwardly; the algorithms of [RFC3986] can be applied directly, treating the characters additionally allowed in IRI references in the same way that unreserved characters are in URI references. -6. Liberal Handling of Otherwise Invalid IRIs +5. Liberal Handling of Otherwise Invalid IRIs - (EDITOR NOTE: This Section may move to an appendix.) Some technical - specifications and widely-deployed software have allowed additional - variations and extensions of IRIs to be used in syntactic components. - This section describes two widely-used preprocessing agreements. - Other technical specifications may wish to reference a syntactic - component which is "a valid IRI or a string that will map to a valid - IRI after this preprocessing algorithm". These two variants are - known as Legacy Extended IRI or LEIRI [LEIRI], and Web Address - [HTML5]). + Some technical specifications and widely-deployed software have + allowed additional variations and extensions of IRIs to be used in + syntactic components. Future technical specifications SHOULD NOT allow conforming producers to produce, or conforming content to contain, such forms, as they are not interoperable with other IRI consuming software. -6.1. LEIRI Processing +5.1. LEIRI Processing This section defines Legacy Extended IRIs (LEIRIs). The syntax of Legacy Extended IRIs is the same as that for , except that the ucschar production is replaced by the leiri-ucschar production: leiri-ucschar = " " / "<" / ">" / '"' / "{" / "}" / "|" / "\" / "^" / "`" / %x0-1F / %x7F-D7FF / %xE000-FFFD / %x10000-10FFFF Among other extensions, processors based on this specification also did not enforce the restriction on bidirectional formatting - characters in Section 4.1, and the iprivate production becomes - redundant. + characters in [Bidi], and the iprivate production becomes redundant. To convert a string allowed as a LEIRI to an IRI, each character allowed in leiri-ucschar but not in ucschar must be percent-encoded using Section 3.3. -6.2. Web Address Processing - - Many popular web browsers have taken the approach of being quite - liberal in what is accepted as a "URL" or its relative forms. This - section describes their behavior in terms of a preprocessor which - maps strings into the IRI space for subsequent parsing and - interpretation as an IRI. - - In some situations, it might be appropriate to describe the syntax - that a liberal consumer implementation might accept as a "Web - Address" or "Hypertext Reference" or "HREF". However, technical - specifications SHOULD restrict the syntactic form allowed by - compliant producers to the IRI or IRI reference syntax defined in - this document even if they want to mandate this processing. - - Summary: - - o Leading and trailing whitespace is removed. - - o Some additional characters are removed. - - o Some additional characters are allowed and escaped (as with - LEIRI). - - o If interpreting an IRI as a URI, the pct-encoding of the query - component of the parsed URI component depends on operational - context. - - Each string provided may have an associated charset (called the HREF- - charset here); this defaults to UTF-8. For web browsers interpreting - HTML, the document charset of a string is determined: - - If the string came from a script (e.g. as an argument to a method) - The HRef-charset is the script's charset. - - If the string came from a DOM node (e.g. from an element) The node - has a Document, and the HRef-charset is the Document's character - encoding. - - If the string had a HRef-charset defined when the string was created - or defined The HRef-charset is as defined. - - If the resulting HRef-charset is a unicode based character encoding - (e.g., UTF-16), then use UTF-8 instead. - - The syntax for Web Addresses is obtained by replacing the 'ucschar', - pct-form, path-sep, and ifragment rules with the href-ucschar, href- - pct-form, href-path-sep, and href-ifragment rules below. In - addition, some characters are stripped. - - href-ucschar = " " / "<" / ">" / DQUOTE / "{" / "}" / "|" - / "\" / "^" / "`" / %x0-1F / %x7F-D7FF - / %xE000-FFFD / %x10000-10FFFF - href-pct-form = pct-encoded / "%" - href-path-sep = "/" / "\" - href-ifragment = *( ipchar / "/" / "?" / "#" ) ; adding "#" - href-strip = - - (NOTE: NEED TO FIX THESE SETS TO MATCH HTML5; NOT SURE ABOUT NEXT - SENTENCE) browsers did not enforce the restriction on bidirectional - formatting characters in Section 4.1, and the iprivate production - becomes redundant. - - 'Web Address processing' requires the following additional - preprocessing steps: - - 1. Leading and trailing instances of space (U+0020), CR (U+000A), LF - (U+000D), and TAB (U+0009) characters are removed. - - 2. strip all characters in href-strip. - - 3. Percent-encode all characters in href-ucschar not in ucschar. - - 4. Replace occurrences of "%" not followed by two hexadecimal digits - by "%25". - - 5. Convert backslashes ('\') matching href-path-sep to forward - slashes ('/'). - -6.3. Characters Not Allowed in IRIs +6. Characters Not Allowed in IRIs This section provides a list of the groups of characters and code - points that are allowed by LEIRI or HREF but are not allowed in IRIs + points that are allowed in some contexts but are not allowed in IRIs or are allowed in IRIs only in the query part. For each group of characters, advice on the usage of these characters is also given, concentrating on the reasons for why they are excluded from IRI use. Space (U+0020): Some formats and applications use space as a delimiter, e.g. for items in a list. Appendix C of [RFC3986] also mentions that white space may have to be added when displaying or printing long URIs; the same applies to long IRIs. This means that spaces can disappear, or can make the what is intended as a single IRI or IRI reference to be treated as two or more separate @@ -1529,21 +1171,21 @@ might allow the user to view an IRI as it is mapped to a URI. Places where the input of IRIs is frequent may provide the possibility for viewing an IRI as mapped to a URI. This will help users when some of the software they use does not yet accept IRIs. An IRI input component interfacing to components that handle URIs, but not IRIs, must map the IRI to a URI before passing it to these components. For the input of IRIs with right-to-left characters, please see - Section 4.3. + [Bidi]. 7.3. URI/IRI Transfer between Applications Many applications (for example, mail user agents) try to detect URIs appearing in plain text. For this, they use some heuristics based on URI syntax. They then allow the user to click on such URIs and retrieve the corresponding resource in an appropriate (usually scheme-dependent) application. Such applications would need to be upgraded, in order to use the IRI @@ -1628,21 +1270,21 @@ Greek, and Cyrillic, using lowercase letters results in fewer ambiguities than using uppercase letters would. 7.6. Display of URIs/IRIs In situations where the rendering software is not expected to display non-ASCII parts of the IRI correctly using the available layout and font resources, these parts should be percent-encoded before being displayed. - For display of Bidi IRIs, please see Section 4.1. + For display of Bidi IRIs, please see [Bidi]. 7.7. Interpretation of URIs and IRIs Software that interprets IRIs as the names of local resources should accept IRIs in multiple forms and convert and match them with the appropriate local resource names. First, multiple representations include both IRIs in the native character encoding of the protocol and also their URI counterparts. @@ -1708,21 +1350,21 @@ encoding for file names will make the transition to IRIs easier. Likewise, when a new Web form is set up using UTF-8 as the character encoding of the form page, the returned query URIs will use UTF-8 as the character encoding (unless the user, for whatever reason, changes the character encoding) and will therefore be compatible with IRIs. These recommendations, when taken together, will allow for the extension from URIs to IRIs in order to handle characters other than US-ASCII while minimizing interoperability problems. For considerations regarding the upgrade of URI scheme definitions, see - Section 5.4. + Section 4.4. 8. IANA Considerations RFC Editor and IANA note: Please Replace RFC XXXX with the number of this document when it issues as an RFC. IANA maintains a registry of "URI schemes". A "URI scheme" also serves an "IRI scheme". To clarify that the URI scheme registration process also applies to @@ -1755,213 +1397,208 @@ User agents SHOULD NOT rely on visual or perceptual comparison or verification of IRIs as a means of validating or assuring safety, correctness or appropriateness of an IRI. Other means of presenting users with the validity, safety, or appropriateness of visited sites are being developed in the browser community as an alternative means of avoiding these difficulties. Besides the large character repertoire of Unicode, reasons for confusion include different forms of normalization and different normalization expectations, use of percent-encoding with various - legacy encodings, and bidirectionality issues. See also [UTR36]. + legacy encodings, and bidirectionality issues. See also [Bidi]. Confusion can occur in various IRI components, such as the domain name part or the path part, or between IRI components. For considerations specific to the domain name part, see [RFC5890]. For considerations specific to particular protocols or schemes, see the security sections of the relevant specifications and registration templates. Administrators of sites that allow independent users to create resources in the same sub area have to be careful. Details are discussed in Section 7.5. - Confusion can occur with bidirectional IRIs, if the restrictions in - Section 4.2 are not followed. The same visual representation may be - interpreted as different logical representations, and vice versa. It - is also very important that a correct Unicode bidirectional - implementation be used. - The characters additionally allowed in Legacy Extended IRIs introduce - additional security issues. For details, see Section 6.3. + additional security issues. For details, see Section 6. 10. Acknowledgements This document was derived from [RFC3987]; the acknowledgments from that specification still apply. - We would like to thank Ian Hickson, Michael Sperberg-McQueen, and Dan - Connolly for their work on HyperText References, and Norman Walsh, - Richard Tobin, Henry S. Thomson, John Cowan, Paul Grosso, and the XML - Core Working Group of the W3C for their work on LEIRIs. - In addition, this document was influenced by contributions from (in - no particular order) Chris Lilley, Bjoern Hoehrmann, Felix Sasaki, - Jeremy Carroll, Frank Ellermann, Michael Everson, Cary Karp, - Matitiahu Allouche, Richard Ishida, Addison Phillips, Jonathan - Rosenne, Najib Tounsi, Debbie Garside, Mark Davis, Sarmad Hussain, - Ted Hardie, Konrad Lanz, Thomas Roessler, Lisa Dusseault, Julian - Reschke, Giovanni Campagna, Anne van Kesteren, Mark Nottingham, Erik - van der Poel, Marcin Hanclik, Marcos Caceres, Roy Fielding, Greg - Wilkins, Pieter Hintjens, Daniel R. Tobias, Marko Martin, Maciej - Stanchowiak, Wil Tan, Yui Naruse, Michael A. Puls II, Dave Thaler, - Tom Petch, John Klensin, Shawn Steele, Peter Saint-Andre, Geoffrey - Sneddon, Chris Weber, Alex Melnikov, Slim Amamou, S. Moonesamy, Tim - Berners-Lee, Yaron Goland, Sam Ruby, Adam Barth, Abdulrahman I. - ALGhadir, Aharon Lanin, Thomas Milo, Murray Sargent, Marc Blanchet, - and Mykyta Yevstifeyev. + no particular order)Norman Walsh, Richard Tobin, Henry S. Thomson, + John Cowan, Paul Grosso, the XML Core Working Group of the W3C, Chris + Lilley, Bjoern Hoehrmann, Felix Sasaki, Jeremy Carroll, Frank + Ellermann, Michael Everson, Cary Karp, Matitiahu Allouche, Richard + Ishida, Addison Phillips, Jonathan Rosenne, Najib Tounsi, Debbie + Garside, Mark Davis, Sarmad Hussain, Ted Hardie, Konrad Lanz, Thomas + Roessler, Lisa Dusseault, Julian Reschke, Giovanni Campagna, Anne van + Kesteren, Mark Nottingham, Erik van der Poel, Marcin Hanclik, Marcos + Caceres, Roy Fielding, Greg Wilkins, Pieter Hintjens, Daniel R. + Tobias, Marko Martin, Maciej Stanchowiak, Wil Tan, Yui Naruse, + Michael A. Puls II, Dave Thaler, Tom Petch, John Klensin, Shawn + Steele, Peter Saint-Andre, Geoffrey Sneddon, Chris Weber, Alex + Melnikov, Slim Amamou, S. Moonesamy, Tim Berners-Lee, Yaron Goland, + Sam Ruby, Adam Barth, Abdulrahman I. ALGhadir, Aharon Lanin, Thomas + Milo, Murray Sargent, Marc Blanchet, and Mykyta Yevstifeyev. 11. Main Changes Since RFC 3987 This section describes the main changes since [RFC3987]. -11.1. Major restructuring of IRI processing model +11.1. Split out Bidi, processing guidelines, comparison sections + + Move some components (comparison, bidi, processing) into separate + documents. + +11.2. Major restructuring of IRI processing model Major restructuring of IRI processing model to make scheme-specific translation necessary to handle IDNA requirements and for consistency with web implementations. Starting with IRI, you want one of: a IRI components (IRI parsed into UTF8 pieces) b URI components (URI parsed into ASCII pieces, encoded correctly) c whole URI (for passing on to some other system that wants whole URIs) -11.1.1. OLD WAY +11.2.1. OLD WAY 1. Pct-encoding on the whole thing to a URI. (c1) If you want a (maybe broken) whole URI, you might stop here. 2. Parsing the URI into URI components. (b1) If you want (maybe broken) URI components, stop here. 3. Decode the components (undoing the pct-encoding). (a) if you want IRI components, stop here. 4. reencode: Either using a different encoding some components (for domain names, and query components in web pages, which depends on the component, scheme and context), and otherwise using pct- encoding. (b2) if you want (good) URI components, stop here. 5. reassemble the reencoded components. (c2) if you want a (*good*) whole URI stop here. -11.1.2. NEW WAY +11.2.2. NEW WAY 1. Parse the IRI into IRI components using the generic syntax. (a) if you want IRI components, stop here. 2. Encode each components, using pct-encoding, IDN encoding, or special query part encoding depending on the component scheme or context. (b) If you want URI components, stop here. 3. reassemble the a whole URI from URI components. (c) if you want a whole URI stop here. -11.1.3. Extension of Syntax +11.2.3. Extension of Syntax Added the tag range (U+E0000-E0FFF) to the iprivate production. Some IRIs generated with the new syntax may fail to pass very strict checks relying on the old syntax. But characters in this range should be extremely infrequent anyway. -11.1.4. More to be added +11.2.4. More to be added TODO: There are more main changes that need to be documented in this section. -11.2. Change Log +11.3. Change Log Note to RFC Editor: Please completely remove this section before publication. -11.2.1. Changes after draft-ietf-iri-3987bis-01 +11.3.1. Changes after draft-ietf-iri-3987bis-01 Changes from draft-ietf-iri-3987bis-01 onwards are available as changesets in the IETF tools subversion repository at http:// trac.tools.ietf.org/wg/iri/trac/log/draft-ietf-iri-3987bis/ draft-ietf-iri-3987bis.xml. -11.2.2. Changes from draft-duerst-iri-bis-07 to +11.3.2. Changes from draft-duerst-iri-bis-07 to draft-ietf-iri-3987bis-00 Changed draft name, date, last paragraph of abstract, and titles in change log, and added this section in moving from draft-duerst-iri-bis-07 (personal submission) to draft-ietf-iri-3987bis-00 (WG document). -11.2.3. Changes from -06 to -07 of draft-duerst-iri-bis +11.3.3. Changes from -06 to -07 of draft-duerst-iri-bis - Major restructuring of the processing model, see Section 11.1. + Major restructuring of the processing model, see Section 11.2. -11.3. Changes from -00 to -01 +11.4. Changes from -00 to -01 o Removed 'mailto:' before mail addresses of authors. o Added "" as right side of 'href-strip' rule. Fixed '|' to '/' for alternatives. -11.4. Changes from -05 to -06 of draft-duerst-iri-bis-00 +11.5. Changes from -05 to -06 of draft-duerst-iri-bis-00 o Add HyperText Reference, change abstract, acks and references for it o Add Masinter back as another editor. o Masinter integrates HRef material from HTML5 spec. o Rewrite introduction sections to modernize. -11.5. Changes from -04 to -05 of draft-duerst-iri-bis +11.6. Changes from -04 to -05 of draft-duerst-iri-bis o Updated references. o Changed IPR text to pre5378Trust200902. -11.6. Changes from -03 to -04 of draft-duerst-iri-bis +11.7. Changes from -03 to -04 of draft-duerst-iri-bis o Added explicit abbreviation for LEIRIs. o Mentioned LEIRI references. o Completed text in LEIRI section about tag characters and about specials. -11.7. Changes from -02 to -03 of draft-duerst-iri-bis +11.8. Changes from -02 to -03 of draft-duerst-iri-bis o Updated some references. o Updated Michel Suginard's coordinates. -11.8. Changes from -01 to -02 of draft-duerst-iri-bis +11.9. Changes from -01 to -02 of draft-duerst-iri-bis o Added tag range to iprivate (issue private-include-tags-115). o Added Specials (U+FFF0-FFFD) to Legacy Extended IRIs. -11.9. Changes from -00 to -01 of draft-duerst-iri-bis +11.10. Changes from -00 to -01 of draft-duerst-iri-bis o Changed from "IRIs with Spaces/Controls" to "Legacy Extended IRI" based on input from the W3C XML Core WG. Moved the relevant subsections to the back and promoted them to a section. o Added some text re. Legacy Extended IRIs to the security section. o Added a IANA Consideration Section. o Added this Change Log Section. o Added a section about "IRIs with Spaces/Controls" (converting from a Note in RFC 3987). -11.10. Changes from RFC 3987 to -00 of draft-duerst-iri-bis +11.11. Changes from RFC 3987 to -00 of draft-duerst-iri-bis Fixed errata (see http://www.rfc-editor.org/cgi-bin/errataSearch.pl?rfc=3987). 12. References 12.1. Normative References [ASCII] American National Standards Institute, "Coded Character Set -- 7-bit American Standard Code for Information @@ -1994,71 +1631,67 @@ [RFC5890] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, August 2010. [RFC5891] Klensin, J., "Internationalized Domain Names in Applications (IDNA): Protocol", RFC 5891, August 2010. [STD68] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. - [UNI9] Davis, M., "The Bidirectional Algorithm", Unicode Standard - Annex #9, March 2004, - . - [UNIV6] The Unicode Consortium, "The Unicode Standard, Version 6.0.0 (Mountain View, CA, The Unicode Consortium, 2011, ISBN 978-1-936213-01-6)", October 2010. [UTR15] Davis, M. and M. Duerst, "Unicode Normalization Forms", Unicode Standard Annex #15, March 2008, . 12.2. Informative References - [BidiEx] "Examples of bidirectional IRIs", - . + [Bidi] Duerst, M. and L. Masinter, "Guidelines for + Internationalized Resource Identifiers with Bi-directional + Characters (Bidi IRIs)", draft-ietf-iri-bidi-guidelines-00 + (work in progress), August 2011. [CharMod] Duerst, M., Yergeau, F., Ishida, R., Wolf, M., and T. Texin, "Character Model for the World Wide Web: Resource Identifiers", World Wide Web Consortium Candidate Recommendation, November 2004, . [Duerst97] Duerst, M., "The Properties and Promises of UTF-8", Proc. 11th International Unicode Conference, San Jose , September 1997, . + [Equivalence] + Masinter, L. and M. Duerst, "Equivalence and + Canonicalization of Internationalized Resource Identifiers + (IRIs)", draft-ietf-iri-comparison-00 (work in progress), + August 2011. + [Gettys] Gettys, J., "URI Model Consequences", . [HTML4] Raggett, D., Le Hors, A., and I. Jacobs, "HTML 4.01 Specification", World Wide Web Consortium Recommendation, December 1999, . - [HTML5] Hickson, I. and D. Hyatt, "A vocabulary and associated - APIs for HTML and XHTML", World Wide Web - Consortium Working Draft, April 2009, - . - [LEIRI] Thompson, H., Tobin, R., and N. Walsh, "Legacy extended IRIs for XML resource identification", World Wide Web Consortium Note, November 2008, . - [RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform - Resource Locators (URL)", RFC 1738, December 1994. - [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. [RFC2130] Weider, C., Preston, C., Simonsen, K., Alvestrand, H., Atkinson, R., Crispin, M., and P. Svanberg, "The Report of the IAB Character Set Workshop held 29 February - 1 March, 1996", RFC 2130, April 1997. [RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997. @@ -2086,22 +1719,22 @@ [RFC2640] Curtin, B., "Internationalization of the File Transfer Protocol", RFC 2640, July 1999. [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource Identifiers (IRIs)", RFC 3987, January 2005. [RFC4395bis] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and Registration Procedures for New URI/IRI Schemes", - draft-hansen-iri-4395bis-irireg-00 (work in progress), - September 2010. + draft-ietf-iri-4395bis-irireg-03 (work in progress), + July 2011. [RFC6055] Thaler, D., Klensin, J., and S. Cheshire, "IAB Thoughts on Encodings for Internationalized Domain Names", RFC 6055, February 2011. [UNIXML] Duerst, M. and A. Freytag, "Unicode in XML and other Markup Languages", Unicode Technical Report #20, World Wide Web Consortium Note, June 2003, .