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Versions: 00 01 02 03 04 05 06 07 08 RFC 6477

Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Informational                                   G. Lunt
Expires: May 25, 2012                                           SMHS Ltd
                                                       November 22, 2011


 Registration of Military Message Handling System (MMHS) header fields
                        for use in Internet Mail
                  draft-melnikov-mmhs-header-fields-08

Abstract

   A Miltary Message Handling System (MMHS) processes formal messages
   ensuring release, distribution, security, and timely delivery across
   national and international strategic and tactical networks.  The MMHS
   Elements of Service are defined as a set of extensions to the ITU-T
   X.400 (1992) international standards and are specified in STANAG 4406
   Edition 2 or ACP 123.  This document specifies message header fields
   and associated processing for RFC 5322 (Internet Email) to provide a
   comparable messaging service.  In addition, this document provides
   for a STANAG 4406 / Internet Email Gateway that supports message
   conversion.

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
   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 May 25, 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



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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  Registration Templates . . . . . . . . . . . . . . . . . . . .  3
     3.1.  Header field: MMHS-Exempted-Address  . . . . . . . . . . .  5
     3.2.  Header field: MMHS-Extended-Authorisation-Info . . . . . .  5
     3.3.  Header field: MMHS-Subject-Indicator-Codes . . . . . . . .  6
     3.4.  Header field: MMHS-Handling-Instructions . . . . . . . . .  6
     3.5.  Header field: MMHS-Message-Instructions  . . . . . . . . .  7
     3.6.  Header field: MMHS-Codress-Message-Indicator . . . . . . .  7
     3.7.  Header field: MMHS-Originator-Reference  . . . . . . . . .  8
     3.8.  Header field: MMHS-Primary-Precedence  . . . . . . . . . .  8
     3.9.  Header field: MMHS-Copy-Precedence . . . . . . . . . . . .  9
     3.10. Header field: MMHS-Message-Type  . . . . . . . . . . . . . 10
     3.11. Header field: MMHS-Other-Recipients-Indicator-To . . . . . 11
     3.12. Header field: MMHS-Other-Recipients-Indicator-Cc . . . . . 11
     3.13. Header field: MMHS-Acp127-Message-Identifier . . . . . . . 12
     3.14. Header field: MMHS-Originator-PLAD . . . . . . . . . . . . 13
   4.  Formal Syntax  . . . . . . . . . . . . . . . . . . . . . . . . 13
   5.  Service in Comparison to ACP 123/STANAG 4406 . . . . . . . . . 15
   6.  Gatewaying with ACP 123/STANAG 4406  . . . . . . . . . . . . . 16
   7.  Gatewaying with ACP 127  . . . . . . . . . . . . . . . . . . . 17
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 18
     10.2. Informative References . . . . . . . . . . . . . . . . . . 19
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 19














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1.  Introduction

   [RFC5322] defines a protocol for the format of electronic messages
   exchanged on the Internet.  MMHS is a military specification defined
   in ACP 123 [ACP123] (also specified in STANAG 4406 [STANAG-4406])
   which defines a number of extensions to the basic X.400 (1992)
   protocol for the services required by military messaging.

   This document supports translating most of the elements of service
   defined in ACP 123 [ACP123] to Internet message header fields (see
   Section 5 for more details).  This specification is written to extend
   the MIXER specification [RFC2156] to enable inter-conversion in a
   MIXER gateway with the X.400 IPMS heading extensions defined in ACP
   123/STANAG 4406 Annex A.

   The document is aimed at the ability to represent MMHS messages as
   RFC 5322 messages.  All RFC 5322 header fields defined in this
   document are prefixed with the string "MMHS-" to distinguish them
   from any other header fields.

   Unless stated otherwise, all header fields described in this document
   are OPTIONAL in an Internet Message.

   This document is structured as follows: Section 3 and its subsections
   formally define new Internet header fields and show some examples.
   Section 4 provides ABNF syntax for them.  Section 5 provides some
   background information about which features of ACP 123/STANAG 4406
   were not implemented in this specification.  Subsequent sections talk
   about additional requirements for gatewaying to/from ACP 123/STANAG
   4406 and ACP 127 [ACP127] environments respectively.

2.  Conventions Used in This Document

   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].

   The formal syntax uses the Augmented Backus-Naur Form (ABNF)
   [RFC5234] notation including the core rules defined in Appendix B of
   RFC 5234 [RFC5234].

3.  Registration Templates

   Header field entries are summarized below in tabular form for
   convenience of reference and presented in full in the following
   subsections.

   Any header field specified in this document MUST NOT appear more than



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   once in message headers.

   +------------------------------------+----------+-------------------+
   | Header name                        | Protocol | Reference         |
   +------------------------------------+----------+-------------------+
   | MMHS-Exempted-Address              | mail     | [ACP123],         |
   |                                    |          | Appendix A1.1 and |
   |                                    |          | Appendix B.105    |
   | MMHS-Extended-Authorisation-Info   | mail     | [ACP123],         |
   |                                    |          | Appendix A1.2 and |
   |                                    |          | Appendix B.106    |
   | MMHS-Subject-Indicator-Codes       | mail     | [ACP123],         |
   |                                    |          | Appendix A1.3 and |
   |                                    |          | Appendix B.107    |
   | MMHS-Handling-Instructions         | mail     | [ACP123][ACP123], |
   |                                    |          | Appendix A1.4 and |
   |                                    |          | Appendix B.108    |
   | MMHS-Message-Instructions          | mail     | [ACP123],         |
   |                                    |          | Appendix A1.5 and |
   |                                    |          | Appendix B.109    |
   | MMHS-Codress-Message-Indicator     | mail     | [ACP123],         |
   |                                    |          | Appendix A1.6 and |
   |                                    |          | Appendix B.110    |
   | MMHS-Originator-Reference          | mail     | [ACP123],         |
   |                                    |          | Appendix A1.7 and |
   |                                    |          | Appendix B.111    |
   | MMHS-Primary-Precedence            | mail     | [ACP123],         |
   |                                    |          | Appendix A1.8 and |
   |                                    |          | Appendix B.101    |
   | MMHS-Copy-Precedence               | mail     | [ACP123],         |
   |                                    |          | Appendix A1.9 and |
   |                                    |          | Appendix B.102    |
   | MMHS-Message-Type                  | mail     | [ACP123],         |
   |                                    |          | Appendix A1.10    |
   |                                    |          | and Appendix      |
   |                                    |          | B.103             |
   | MMHS-Other-Recipients-Indicator-To | mail     | [ACP123],         |
   |                                    |          | Appendix A1.12    |
   |                                    |          | and Appendix      |
   |                                    |          | B.113             |
   | MMHS-Other-Recipients-Indicator-Cc | mail     | [ACP123],         |
   |                                    |          | Appendix A1.12    |
   |                                    |          | and Appendix      |
   |                                    |          | B.113             |
   | MMHS-Acp127-Message-Identifier     | mail     | [ACP123],         |
   |                                    |          | Appendix A1.14    |
   |                                    |          | and Appendix      |
   |                                    |          | B.116             |



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   | MMHS-Originator-PLAD               | mail     | [ACP123],         |
   |                                    |          | Appendix A1.15    |
   |                                    |          | and Appendix      |
   |                                    |          | B.117             |
   +------------------------------------+----------+-------------------+

3.1.  Header field: MMHS-Exempted-Address

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor4: this document]]

   The exempted address header field, by its presence, indicates the
   addresses of members in an Address List (AL) that should not receive
   the message.  If this header field is absent from the message, all
   members of an AL will be considered to be valid recipients of the
   message.  Note: There is no guarantee that the exempted addresses
   will not receive the message as the result of redirection,
   Distribution List (DL) expansion, etc.

   Example:
   MMHS-Exempted-Address: UK SHL CGT Samuals G
    <graham.samuals@shl.example.com>, UK SHL Duty Officer
   <duty@shl.example.com>

3.2.  Header field: MMHS-Extended-Authorisation-Info

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor6: this document]]

   The extended authorisation info header field, by its presence,
   indicates either the date and the time when the message was
   officially released by the releasing officer or the date and time
   when the message was initially submitted to a communication facility
   for transmission.

   This header field SHOULD always be present in an email message which
   complies with this specification.

   Example:
   MMHS-Extended-Authorisation-Info:
    Mon, 09 Aug 2010 15:27:40 +0100

   The example above demonstrates use of folding white space (FWS
   [RFC5322]).



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3.3.  Header field: MMHS-Subject-Indicator-Codes

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor8: this document]]

   Subject Indicator Codes (SICs) are a mechanism for formally
   identifying the topic of a message.  SICs are nested codes that
   provide information for message distribution after delivery to the
   recipient organisation.  SIC codes are usually three letters or three
   letters and digits, but may be up to 8 characters long.  Nations and
   organizations using SIC codes usually maintain a central registry.

   When present a MMHS-Subject-Indicator-Codes header field contains one
   or more SICs, which indicates distribution information to a recipient
   or a recipient's User Agent.  This information can be used to perform
   automatic or manual local distribution of a message.  If the MMHS-
   Subject-Indicator-Codes header field is absent, then the local
   distribution will be in accordance with the message handling policy
   of the recipient's domain.

   [ACP123] specifies two optional components of the Distribution Code
   Element of Service.  The MMHS-Subject-Indicator-Codes header field
   covers only the SIC code variant of distribution codes.

   Example:
   MMHS-Subject-Indicator-Codes: SDM; KKZ ; BRL

   The example above includes 3 SIC codes: "SDM" (GROUND/LAND
   REQUIREMENTS), "KKZ" (HELICOPTER PUBLICATIONS/MANUALS) and "BRL"
   (HILEX INCIDENTS).

3.4.  Header field: MMHS-Handling-Instructions

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor10: this document]]

   The handling instructions header field, by its presence, indicates
   human readable local handling instructions that requires some manual
   handling by a traffic operator.  If this header field is absent the
   message will be considered as not requiring manual handling by a
   traffic operator.

   Handling instructions (also called transmission instructions) are a
   part of format line 4 as defined in ACP 127 [ACP127], and concern the



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   sending of the message, e.g. that a particular system shall be used
   for transfer of the message.

   This header field is used to support interoperability with ACP 127
   systems.

   Example:
   MMHS-Handling-Instructions: RXFPA ZOV MINDEF

   The example above includes one ACP 131(F) handling instruction:
   "RXFPA ZOV MINDEF".  The "ZOV MINDEF" indicates that MINDEF rerouted
   the message for some reason, and the correct routing is via RXFPA.

3.5.  Header field: MMHS-Message-Instructions

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor12: this document]]

   The message instructions header field, by its presence, indicates
   message instructions (also known as "remarks") accompanying the
   message (e.g., similar to the operating signals specified in ACP 131
   [ACP131]).  If this header field is absent the message will be
   considered received without message instructions.

   The difference between Handling instructions and Message instructions
   is that the former is only for manual handling by traffic operators,
   while the latter also contains information of interest to the persons
   reading the message.

   Example:
   MMHS-Message-Instructions: MINIMIZE CONSIDERED; NO DISTRIBUTION

   The example above includes 2 ACP123(B) [ACP123] defined message
   instructions: "MINIMIZE CONSIDERED" indicating that the originating
   user has considered the Minimize status of the recipients and "NO
   DISTRIBUTION", indicating that the recipients should not distribute
   the message further without the originating user's approval.

3.6.  Header field: MMHS-Codress-Message-Indicator

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor14: this document]]

   The codress message indicator header field, by its presence,



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   indicates that the message is in Codress format.  If this header
   field is absent the message will be considered received without the
   Codress format.

   A Codress message is one in which all addresses, i.e. the sender and
   all recipients, is encrypted within the ACP 127 text (body) [ACP127].
   The heading of any Codress message contains only the minimum of
   information which will enable a receiving station to deal properly
   and expeditiously with the particular transmission.  The general
   rules for the preparation and transmission of Codress messages are
   given in ACP 121 [ACP121].

   This header field is used only to support interoperability with ACP
   127 systems.

   Example:
   MMHS-Codress-Message-Indicator: 23

3.7.  Header field: MMHS-Originator-Reference

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor16: this document]]

   The originator reference header field, by its presence, indicates a
   user defined reference called the "originator's number".  If this
   header field is absent, then the message will be considered received
   without any user defined reference.

   The "originator's number" is used by the originating organisational
   unit and is further qualified within national policy.

   Note: trailing and leading spaces in an originator reference are not
   allowed by syntax.

   Example:
   MMHS-Originator-Reference: IMSCOM-JIC-612-78

3.8.  Header field: MMHS-Primary-Precedence

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor18: this document]]

   The primary precedence header field, by its presence, indicates the
   precedence level of the primary ("action") recipients.  The message



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   originating domain MUST ensure that this header field is always
   present if the message contains "To:" ("action") addresses.

   The MMHS Primary Precedence Element of Service indicates the relative
   order in which Military Messages are to be handled for primary
   (action) recipients, i.e. a Military Message with higher MMHS-
   Primary-Precedence header field value SHOULD be handled before a
   Military Message with a lower MMHS-Primary-Precedence header field
   value.

   The header field value is a non-negative integer, or one of the 6
   predefined case-insensitive labels: "deferred" (same as "0"),
   "routine" (same as "1"), "priority" (same as "2"), "immediate" (same
   as "3"), "flash" (same as "4"), or "override" (same as "5"),
   optionally followed by a comment.  Note that according to ACP 123
   values in the range from 0 to 15 are reserved for NATO defined
   precedence levels and values in the range from 16 to 31 are reserved
   for national users.

   Example 1:
   MMHS-Primary-Precedence: 0 (Deferred)

   Example 2:
   MMHS-Primary-Precedence: FLASH

   Example 3:
   MMHS-Primary-Precedence: 7

3.9.  Header field: MMHS-Copy-Precedence

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor20: this document]]

   The copy precedence header field, by its presence, indicates the
   precedence level of the copy ("information") recipients.  The message
   originating domain MUST ensure that this header field is always
   present if the message contains "Cc:" or "Bcc:" ("information")
   addresses.

   The MMHS Copy Precedence Element of Service indicates the relative
   order in which Military Messages are to be handled for copy
   (information) recipients. i.e. a Military Message with higher MMHS-
   Copy-Precedence header field value SHOULD be handled before a
   Military Message with a lower MMHS-Copy-Precedence header field
   value.




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   The header field value is a non-negative integer, or one of the 6
   predefined case-insensitive labels: "deferred" (same as "0"),
   "routine" (same as "1"), "priority" (same as "2"), "immediate" (same
   as "3"), "flash" (same as "4"), or "override" (same as "5"),
   optionally followed by a comment.  Note that according to ACP 123
   values in the range from 0 to 15 are reserved for NATO defined
   precedence levels and values in the range from 16 to 31 are reserved
   for national users.

   Example 1:
   MMHS-Copy-Precedence: 2 (priority)

   Example 2:
   MMHS-Copy-Precedence: Priority

3.10.  Header field: MMHS-Message-Type

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor22: this document]]

   The message type heading extension, by its presence, indicates
   whether the message is to be considered as an exercise, an operation,
   a project or a drill.  (Note that the list of types is extensible and
   other types can be specified using the numeric form, see below.)  It
   may include an optional parameter specifying the name of the
   exercise, operation, project or drill.  If this extension is absent
   the message will be considered to be of an undefined type.

   The header field value is a non-negative integer, or one of the 4
   predefined case-insensitive labels: "exercise" (same as "0"),
   "operation" (same as "1"), "project" (same as "2"), "drill" (same as
   "3").  Note that according to ACP 123 values in the range from 0 to
   127 are reserved for NATO defined Message Type identifiers and values
   in the range from 128 to 255 are not defined by NATO and may be used
   nationally or bilaterally.

   Example 1:
   MMHS-Message-Type: 0(exercise); identifier="CANDLE FISH"

   Example 2:
   MMHS-Message-Type: 3

   Example 3:
   MMHS-Message-Type: 2 (projet)

   Example 4:



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   MMHS-Message-Type: project

   Note that some of the examples above demonstrate use of optional
   comments.  See Section 4 for the exact syntax of this header field.

3.11.  Header field: MMHS-Other-Recipients-Indicator-To

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor23: this document]]

   The other primary recipients indicator header field, by its presence,
   indicates the names of primary recipients that are intended to
   receive or have received the message via means other than MMHS.  Note
   that the absence of both this header field and the MMHS-Other-
   Recipients-Indicator-Cc header field (see Section 3.12 does not
   guarantee that all recipients are within the MMHS.

   This header field enables a recipient to determine all action
   recipients of a Military Message.  This header field is derived from
   the Other Recipient Info Element of Service.

   There are several reasons as to why a recipient of a Military Message
   may be identified by this header:

   1.  The recipient is not part of the MMHS

   2.  The path to the recipient through the MMHS may not be secure,
       therefore, the originator has used alternative mechanisms to
       distribute the Military Message

   3.  The recipient was already in receipt of the Military Message
       prior to the Military Message being inserted into the MMHS

   Example:
   MMHS-Other-Recipients-Indicator-To: UK SHL COS; UK SHL IM

   The example above includes names of 2 primary recipients which
   received the message via means other than MMHS.

3.12.  Header field: MMHS-Other-Recipients-Indicator-Cc

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor24: this document]]




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   The other copy recipients indicator header field, by its presence,
   indicates the names of copy recipients that are intended to receive
   or have received the message via means other than MMHS.  Note that
   the absence of both this header field and the MMHS-Other-Recipients-
   Indicator-To header field (see Section 3.11 does not guarantee that
   all recipients are within the MMHS.

   This header field enables a recipient to determine all copy
   recipients of a Military Message.  This header field is derived from
   the Other Recipient Info Element of Service.

   There are several reasons as to why a recipient of a Military Message
   may be identified by this header:

   1.  The recipient is not part of the MMHS

   2.  The path to the recipient through the MMHS may not be secure,
       therefore, the originator has used alternative mechanisms to
       distribute the Military Message

   3.  The recipient was already in receipt of the Military Message
       prior to it being inserted into the MMHS

   Example:
   MMHS-Other-Recipients-Indicator-Cc: UK SHL LEGAD

   The example above includes 1 copy (information) recipient which
   received the message via means other than MMHS.

3.13.  Header field: MMHS-Acp127-Message-Identifier

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor26: this document]]

   The ACP127 message identifier header field, by its presence,
   indicates an ACP 127 message identifier [ACP127] for a message that
   originated from an ACP 127 domain.  If this extension is absent, then
   the message did not encounter an ACP 127 domain.

   The acp127-message-identifier contains the contents of ACP127 format
   line 3 consisting of three space (SP) separated fields: the Calling
   Station (DERI), Station Serial Number (SSN), and Filing Time (JFT)
   [ACP127].

   This header field is used only to support interoperability with ACP
   127 systems, it should be treated as opaque by a pure MMHS system.



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   Example:
   MMHS-Acp127-Message-Identifier: RPDLE 1234 0341215

3.14.  Header field: MMHS-Originator-PLAD

   Applicable protocol: mail [RFC5322]
   Status: informational
   Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF
   Specification document(s): [[anchor28: this document]]

   The originator Plain Language Address Designators (PLAD) header
   field, by its presence, indicates the plain language address
   associated with an originator for cross-reference purposes.  If this
   header field is absent, then the message will be considered to not
   having an originators PLAD cross reference between the MMHS and ACP
   127 domains.

   This header field is used only to support interoperability with ACP
   127 systems.

   This header field and the Extended Authorisation Info header field
   provide a cross-reference for message identification in both ACP 127
   and MMHS domains.

   Example:
   MMHS-Originator-PLAD: SACLANT

4.  Formal Syntax

   The following syntax specification uses the Augmented Backus-Naur
   Form (ABNF) as described in [RFC5234].  Terms not defined here are
   taken from [RFC5322], [RFC5234] and [RFC2156].

    NZ-DIGIT       =  %x31-39
                      ; "1".."9"

    nonneg-integer = "0" / (NZ-DIGIT *DIGIT)

    military-string = 1*69( ps-char )

    quoted-military-string = DQUOTE military-string DQUOTE

    military-string-sequence = military-string
                        *( [FWS] ";" [FWS] military-string )

    Exempted-Address = "MMHS-Exempted-Address:"
                       [FWS] address-list [FWS] CRLF




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    Extended-Authorisation-Info = "MMHS-Extended-Authorisation-Info:"
                                  [FWS] date-time CRLF

    Subject-Indicator-Codes = "MMHS-Subject-Indicator-Codes:"
                              [FWS] sic-sequence [FWS] CRLF

    sic-sequence = sic *( [FWS] ";" [FWS] sic )
                   ; ACP 123 specifies that the maximum number of
                   ; SICs is 8. Use of more than 8 SIC codes is
                   ; permitted, but additional SIC codes might not
                   ; be transferred to ACP 123 system.

    sic = 3*8( ps-char )

    Handling-Instructions = "MMHS-Handling-Instructions:"
                            [FWS] military-string-sequence [FWS] CRLF

    Message-Instructions = "MMHS-Message-Instructions:"
                           [FWS] military-string-sequence [FWS] CRLF

    Codress-Message-Indicator = "MMHS-Codress-Message-Indicator:"
                                [FWS] nonneg-integer [FWS] CRLF

    Originator-Reference = "MMHS-Originator-Reference:"
                           [FWS] military-string [FWS] CRLF

    PrimaryPrecedence = "MMHS-Primary-Precedence:" [FWS] precedence CRLF

    CopyPrecedence = "MMHS-Copy-Precedence:" [FWS] precedence CRLF

    precedence = (nonneg-integer / std-precedence) [CFWS]

    std-precedence = "deferred" / "routine" / "priority" /
                     "immediate" / "flash" / "override"
                     ; deferred == 0
                     ; routine == 1
                     ; priority == 2
                     ; immediate == 3
                     ; flash == 4
                     ; override == 5

    MessageType = "MMHS-Message-Type:" [FWS] message-type [CFWS]
                  [";" [FWS] MessageTypeParam [FWS] ] CRLF

    message-type = nonneg-integer / std-message-type

    std-message-type = "exercise" / "operation" / "project" /  "drill"
                       ; exercise  == 0



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                       ; operation == 1
                       ; project == 2
                       ; drill == 3

    MessageTypeParam = "identifier" [FWS] "=" [FWS]
                       quoted-military-string

    Designator = military-string

    OtherRecipIndicatorPrimary = "MMHS-Other-Recipients-Indicator-To:"
                         [FWS] Designator *([FWS] ";" [FWS] Designator)
                         [FWS] CRLF

    OtherRecipIndicatorCopy = "MMHS-Other-Recipients-Indicator-Cc:"
                         [FWS] Designator *([FWS] ";" [FWS] Designator)
                         [FWS] CRLF

    Acp127MessageIdentifier = "MMHS-Acp127-Message-Identifier:"
                              [FWS] military-string [FWS] CRLF

    OriginatorPLAD = "MMHS-Originator-PLAD:" [FWS] military-string [FWS]
                     CRLF

    address-list = <Defined in RFC 5322>

5.  Service in Comparison to ACP 123/STANAG 4406

   The service specified in this document is a subset of the
   functionality set out in Annex A1 "Military Heading Extensions" of
   [ACP123].  The majority of this functionality is supported in this
   document.  A few capabilities have been left out which would have
   significantly increased the complexity of this specification.

   For Distribution Codes (A.1.3) only Subject Indicator Codes are
   supported and Distribution Extensions are omitted.  Authors of this
   document believe that distribution extensions are not widely used.

   Address List Indication (A.1.11) is not supported.  This complex
   extension is deprecated in [ACP123].

   Pilot Forwarding Information (A.1.13) is not supported.

   Security Information Labels (A.1.16) is not supported.  This
   extension is deprecated in favour of Annex A of [ACP123], which uses
   ESS Labels [RFC2634] which can be supported in a directly compatible
   manner in S/MIME [RFC5751].

   ACP 127 Notification Requests (A.2.1) and Responses (A.3.1) are not



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   supported.  These extensions are used to request and return
   notifications from ACP 127 gateways, and are not relevant to an SMTP
   gateway.

6.  Gatewaying with ACP 123/STANAG 4406

   The header fields defined in this specification are designed to be
   mapped with ACP 123 Annex A1 heading extensions as part of a MIXER
   mapping according to [RFC2156].  The syntax of these headings is
   defined such that mapping is mechanical.  OR Names SHOULD be mapped
   with Internet Email addresses according to [RFC2156].

   This section summarizes how a gateway between [ACP123] and [RFC5322]
   conformant to this specification operates.

   If an incoming X.400 message is encoded as P772, [RFC5322] header
   fields MUST be generated according to this specification for all ACP
   123 heading extensions where an equivalent header is defined in this
   specification.  For the three heading extensions where no mapping is
   defined the heading extension MAY be discarded or mapped in a
   proprietary manner.  If a Distribution Extension is encoded this MAY
   be discarded or represented as a comment (<CFWS>).  The whole message
   MAY be signed according to [RFC5652].  These rules also apply to
   heading extensions in forwarded messages.  MM-Message MUST be treated
   as a forwarded message for the purposes of MIXER mapping.  If an ACP
   127 Notification Request is present, this MAY be discarded or
   represented as a comment (<CFWS>).

   Incoming X.400 notifications are encoded according to [RFC2156].  If
   an ACP 127 Notification Response is present, this MAY be discarded or
   mapped in a proprietary manner.

   If an incoming SMTP message contains any of the header fields defined
   in this specification, the outgoing X.400 message MUST be encoded as
   P772.  The outgoing message MAY be encoded as P772 for other reasons,
   such as policy or characteristics such as the message containing a
   military body part.  The X.400 message might be signed according to
   ACP 123 Annex B [ACP123] or STANAG 4406 Annex G [STANAG-4406].
   message/rfc822 body parts included in the message SHOULD be mapped to
   MM-Message, and the heading mapping rules applied.

   Generated P772 messages SHOULD follow the following rules, generating
   heading extensions if needed.

   a.  Extended Authorization is required.  If the MMHS-Extended-
       Authorisation-Info header field is absent, then the default value
       is taken from the Date: header field.




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   b.  Primary Precedence is required if the To header field is present.
       If the MMHS-Primary-Precedence header field is absent, the
       message need not be considered a military message and can be
       handled according to a local policy.

   c.  Copy Precedence is required if the Cc header field is present.
       If the MMHS-Copy-Precedence header field is absent, the message
       need not be considered a military message and can be handled
       according to a local policy.

   d.  For Message-ID fields, ACP 123 applies additional constraints
       over X.400, leading to the following rules additional to
       [RFC2156] which SHOULD be followed by a gateway following this
       specification.

       1.  The local identifier MUST be at least 15 characters long.  If
           the [RFC2156] generated value is shorter than this, then it
           is padded with spaces to 15 characters.  This value will
           correctly reverse map.

       2.  The OR Address part is required, and not usually generated by
           an [RFC2156] mapping.  It is mandatory in ACP 123.  The
           gateway SHOULD generate an OR Address in a manner that can be
           reverse mapped.  It MAY use the OR Address to encode long
           message ids that cannot be encoded in the local identifier.

7.  Gatewaying with ACP 127

   The header fields defined in this specification include fields to
   carry ACP 127 specific elements of service [ACP127].  This
   specification does not define a mapping of these header fields to ACP
   127.  In the absence of this mapping, it is recommended that these
   heading should be mapped to ACP 123 and hence into ACP 127 following
   the Annex D (Gateway Translation) of [STANAG-4406].

8.  IANA Considerations

   IANA is requested to add the list of header fields specified in
   subsections of Section 3 to the "Permanent Message Header Field
   Registry", defined by Registration Procedures for Message Header
   Fields [RFC3864].

9.  Security Considerations

   Annex B of [ACP123] describes how MMHS messages can be protected in
   an X.400 environment.  Similar protection can be provided using
   S/MIME [RFC5751] and/or DKIM [RFC4871].  In particular, DKIM can be
   used to protect against alteration, deletion or insertion of header



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   fields specified in this document which can affect disposition and
   quality of service applied to processing of the protected Internet
   message by receiving gateways/endpoints which support this
   specification.  (Note that most of the header fields defined in this
   document might affect processing of the message by the receiving
   gateway/end system, MMHS-Subject-Indicator-Codes and MMHS-Primary-
   Precedence/MMHS-Copy-Precedence header fields being the most
   important examples.  For example alteration of the MMHS-Primary-
   Precedence header field value might affect processing speed of the
   message by the recipient MTA.)

   When the original message header fields are digitally signed, the act
   of gatewaying messages with such header fields to/from an Internet
   environment from/to an ACP 123 environment breaks digital signatures.
   The gateway can sign the translated message itself (e.g. with DKIM),
   but a message recipient would be unable to verify that the message
   was generated by the original sender.

10.  References

10.1.  Normative References

   [RFC2119]      Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5322]      Resnick, P., Ed., "Internet Message Format", RFC 5322,
                  October 2008.

   [RFC5234]      Crocker, D. and P. Overell, "Augmented BNF for Syntax
                  Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC2156]      Kille, S., "MIXER (Mime Internet X.400 Enhanced
                  Relay): Mapping between X.400 and RFC 822/MIME",
                  RFC 2156, January 1998.

   [RFC3864]      Klyne, G., Nottingham, M., and J. Mogul, "Registration
                  Procedures for Message Header Fields", BCP 90,
                  RFC 3864, September 2004.

   [RFC4871]      Allman, E., Callas, J., Delany, M., Libbey, M.,
                  Fenton, J., and M. Thomas, "DomainKeys Identified Mail
                  (DKIM) Signatures", RFC 4871, May 2007.

   [RFC5652]      Housley, R., "Cryptographic Message Syntax (CMS)",
                  STD 70, RFC 5652, September 2009.

   [ACP123]       CCEB, "Common Messaging strategy and procedures",
                  ACP 123, May 2009.



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   [ACP127]       CCEB, "Communication Instructions - Tape Relay
                  Procedures", ACP 127, November 1988.

10.2.  Informative References

   [RFC2634]      Hoffman, P., "Enhanced Security Services for S/MIME",
                  RFC 2634, June 1999.

   [RFC5751]      Ramsdell, B. and S. Turner, "Secure/Multipurpose
                  Internet Mail Extensions (S/MIME) Version 3.2 Message
                  Specification", RFC 5751, January 2010.

   [STANAG-4406]  NATO, "STANAG 4406 Edition 2: Military Message
                  Handling System", STANAG 4406, March 2005.

   [ACP121]       CCEB, "Comms Instructions - General", ACP 121,
                  May 2010.

   [ACP131]       CCEB, "Comms Instructions - Operating Signals",
                  ACP 131, April 2009.

Appendix A.  Acknowledgements

   This document copies lots of text from
   draft-onions-x400p772-822-mapping-01.txt and STANAG 4066 (2nd
   Edition).  So the authors of this document would like to acknowledge
   contributions made by the authors of these documents.

   Many thanks for reviews and text provided by Steve Kille, Alan Ross,
   David Wilson, James Usmar, Kathy Nuckles, Andy Trayler, Ken Carlberg,
   Chris Bonatti, Oeyvind Jonsson, Mykyta Yevstifeyev, Sean Turner,
   Stephen Farrell, Adrian Farrel and Peter Saint-Andre.

Authors' Addresses

   Alexey Melnikov
   Isode Ltd
   5 Castle Business Village
   36 Station Road
   Hampton, Middlesex  TW12 2BX
   UK

   EMail: Alexey.Melnikov@isode.com








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   Graeme Lunt
   SMHS Ltd
   Bescar Moss Farm
   Bescar Lane
   Ormskirk  L40 9QN
   UK

   EMail: graeme.lunt@smhs.co.uk











































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