XEP-0394: Message Markup

This specification provides an alternative to XHTML-IM with rigid separation of content and markup information, improving the resilience against spoofing and injection attacks.
Konstzntin Kozlov
© 2017 – 2019 XMPP Standards Foundation. SEE LEGAL NOTICES.


WARNING: This document has been automatically Deferred after 12 months of inactivity in its previous Experimental state. Implementation of the protocol described herein is not recommended for production systems. However, exploratory implementations are encouraged to resume the standards process.
Standards Track
0.2.1 (2019-01-05)
Document Lifecycle
  1. Experimental
  2. Deferred
  3. Proposed
  4. Stable
  5. Final

1. Introduction

Currently, XHTML-IM (XEP-0071) [1] or ad-hoc text-based formats are used to provide styling and semantic information in messages sent over the XMPP network.

These approaches have several drawbacks, including but not limited to:

2. Requirements

3. Glossary


4. Use Cases

4.1 Transport inline markup

Inline markup is declared with the <span/> element.

Example 1.
  <body>There is really no reason to worry.</body>
  <markup xmlns="urn:xmpp:markup:0">
    <span start="9" end="15">

The following child elements are defined for <span/>:

The start and end attributes define the range at which the span is applied. They are in units of unicode code points in the character data if the body element. The first affected codepoint is the one at start (where the first codepoint of a message has index 0) and the last affected codepoint is the one just before end. The above example could render in HTML as:

There is really no reason to worry.

4.2 Transport code blocks

Code blocks are declared with the <bcode/> element:

Example 2.
  <body>Just run this command:
$ cowsay XMPP is awesome.</body>
  <markup xmlns="urn:xmpp:markup:0">
    <bcode start="23" end="48"/>

The start and end attributes work just like for <span/>.

The suggested rendering of code blocks is as block-level elements with monospaced font. The above example could render in HTML as:

Just run this command:

$ cowsay XMPP is awesome.

4.3 Transport itemized lists

Itemized lists are declared with the <list/> and <li/> elements:

Example 3.
  <body>This XEP supports many things:
* inline markup
* code blocks
* lists
* and possibly more!</body>
  <markup xmlns="urn:xmpp:markup:0">
    <list start="31" end="89">
      <li start="31"/>
      <li start="47"/>
      <li start="61"/>
      <li start="69"/>

The start and end attributes of <list/> define the scope of the list. The start of the <li/> elements denote the start of a new list item. A list item continues until the end of the list or the start of the next list item. The first <li/> in a <list/> MUST have a start value equal to the start value of the <list/>.

The above example could render in HTML as:

This XEP supports many things:

4.4 Transport blockquotes

A block quote is declared with a <bquote/> element:

Example 4.
  <body>He said:
&gt; Thou shalt not pass!
and raised his hand.</body>
  <markup xmlns="urn:xmpp:markup:0">
    <bquote start="9" end="32"/>

In addition, References (XEP-0372) [3] or a similar mechanism MAY be used to attribute the origin of the quote. The above example could render in HTML as:

He said:

> Thou shalt not pass!

and raised his hand.

A nested quotation can be created by adding two <bquote/> elements where the start/end range is nested. If plain text quotation markers are used, the start of the blockquote MUST be placed at the first quotation marker of the outer quote.

Example 5.
  <body>&gt; He said:
&gt;&gt; Thou shalt not pass!
&gt; and raised his hand.

Isn't this from some famous movie?</body>
  <markup xmlns="urn:xmpp:markup:0">
    <bquote start="0" end="57"/>
    <bquote start="11" end="34"/>

The above example could render in HTML as:

> He said:
>> Thou shalt not pass!
> and raised his hand.

Isn't this from some famous movie?

5. Business Rules

6. Implementation Notes


7. Accessibility Considerations

Entities are encouraged use the semantic information to make the presentation of the textual content more precise, for example by applying spoken emphasis to passages marked with an <emphasis/> <span/>.

8. Internationalization Considerations

Since a message may have multiple <body/> elements in different languages, there MAY be multiple <markup/> elements, one for each of the <body/> elements. There is no requirement to include a <markup/> element for each language.

9. Security Considerations


10. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [4].

11. XMPP Registrar Considerations

This specification defines the following XML namespaces:

12. XML Schema

REQUIRED for protocol specifications.

13. Acknowledgements

Thanks to Georg Lukas and Emmanuel Gil Peyrot for feedback on the initial idea of this XEP.


Appendix A: Document Information

XMPP Standards Foundation
Standards Track
Last Updated
Approving Body
XMPP Council
Superseded By
Short Name
Source Control

This document in other formats: XML  PDF

Appendix B: Author Information

Konstzntin Kozlov


This XMPP Extension Protocol is copyright © 1999 – 2024 by the XMPP Standards Foundation (XSF).


Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.

Disclaimer of Warranty

## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ##

Limitation of Liability

In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.

IPR Conformance

This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <https://xmpp.org/about/xsf/ipr-policy> or obtained by writing to XMPP Standards Foundation, P.O. Box 787, Parker, CO 80134 USA).

Visual Presentation

The HTML representation (you are looking at) is maintained by the XSF. It is based on the YAML CSS Framework, which is licensed under the terms of the CC-BY-SA 2.0 license.

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <https://xmpp.org/community/> for a complete list.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".

Appendix G: Notes

1. XEP-0071: XHTML-IM <https://xmpp.org/extensions/xep-0071.html>.

2. Security Issues with XHTML-IM (again) <https://mail.jabber.org/pipermail/standards/2017-October/033546.html>.

3. XEP-0372: References <https://xmpp.org/extensions/xep-0372.html>.

4. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>.

Appendix H: Revision History

Note: Older versions of this specification might be available at https://xmpp.org/extensions/attic/

  1. Version 0.2.1 (2019-01-05)
    Adopt deferred XEP.
  2. Version 0.2.0 (2018-12-06)
    Defer due to lack of activity.
    XEP Editor (jsc)
  3. Version 0.1.0 (2017-11-22)

    First draft approved by the XMPP Council.

    XEP Editor (ssw)
  4. Version 0.0.1 (2017-11-07)

    First draft.


Appendix I: Bib(La)TeX Entry

  title = {Message Markup},
  author = {Kozlov, Konstzntin},
  type = {XEP},
  number = {0394},
  version = {0.2.1},
  institution = {XMPP Standards Foundation},
  url = {https://xmpp.org/extensions/xep-0394.html},
  date = {2017-11-07/2019-01-05},