XEP-0457: Message Fancying

This specification defines a Unicode-formatted fancy text syntax for use in instant messages.
Georg Lukas
© 2021 – 2021 XMPP Standards Foundation. SEE LEGAL NOTICES.


NOTICE: This document is Humorous. It MAY provide amusement but SHOULD NOT be taken seriously.
XEP-0071, XEP-0393, XEP-0394
1.0.0 (2021-04-01)
Document Lifecycle
  1. Active

1. Introduction

XMPP-based Instant Messages has suffered from a lack of proper message styling mechanisms. After abandoning XHTML-IM (XEP-0071) [1] for its horrible security track record, Message Styling (XEP-0393) [2] and Message Markup (XEP-0394) [3] were proposed as replacements, but neither was able to gain sufficient traction to become the default styling mechanism.

This specification fills the gap by formally specifying the Unicode-based formatting that is currently fancied on Social Media and micro-blogging as an XMPP standard for Instant Messaging. As XMPP is based on UTF-8, messages formatted with this mechanism are immediately visible on all receiving clients. Simple third-party tools can be used for writing messages until this specification is integrated into the IM message input boxes.

2. Requirements

This specification relies on Unicode features introduced in the 3.1 specification. As XMPP implementations are required to support Unicode 3.2 for StringPrep during SASL authentication, no new requirements arise.

3. Use Cases

4. Business Rules

4.1 Preformatted Text

To format a string as Preformatted Text, the individual code-points need to be converted to their integer representation, then increased by 0x1D62F (capital letters) or 0x1D629 (lowercase letters) and then converted back to characters.

Preformatted text → 𝙿𝚛𝚎𝚏𝚘𝚛𝚖𝚊𝚝𝚝𝚎𝚍 𝚝𝚎𝚡𝚝

4.2 Emphasis

To format a string with Emphasis, the individual code-points need to be converted to their integer representation, then increased by 0x1D3F3 (capital letters) or 0x1D3ED (lowercase letters) and then converted back to characters.

Emphasis → 𝐸𝑚𝑝ℎ𝑎𝑠𝑖𝑠

4.3 Strong Emphasis

To format a string with Strong Emphasis, the individual code-points need to be converted to their integer representation, then increased by 0x1D3BF (capital letters) or 0x1D3B9 (lowercase letters) and then converted back to characters.

Strong Emphasis → 𝐒𝐭𝐫𝐨𝐧𝐠 𝐄𝐦𝐩𝐡𝐚𝐬𝐢𝐬

4.4 Very Strong Emphasis

To format a string with Very Very Strong Emphasis, the individual code-points need to be converted to their integer representation, then increased by 0x1D427 (capital letters) or 0x1D421 (lowercase letters) and then converted back to characters.

Very Strong Emphasis → 𝑽𝒆𝒓𝒚 𝑺𝒕𝒓𝒐𝒏𝒈 𝑬𝒎𝒑𝒉𝒂𝒔𝒊𝒔

4.5 Strike through

To format a string as struck through, each code-point needs to be extended with a U-0336 COMBINING LONG STROKE OVERLAY postfix.

Strike through → S̶t̶r̶i̶k̶e̶ ̶t̶h̶r̶o̶u̶g̶h̶

5. Implementation Notes

Some clients will use a serif-less font instead of a serif font to display instant messages, or even allow the user to choose an arbitrary font. The formatting defined in this document assumes the use of serif fonts, however. If a formatted text is to be displayed in a context that is not supposed to render serifs, the displaying implementation MUST add 0x1D4 to the respective integer representations of the fancy code-points.

On the wire, the serif representation always MUST be used.

Determining whether a given display font is serif or sans-serif is out of scope of this specification.

6. Accessibility Considerations


7. Internationalization Considerations


8. Security Considerations

The rendering of fonts is a complex task performed in the most inner guts of the operating system. Over the last decades, various exploits have been discovered in all major operating systems. Unfortunately, fixing those issues is far beyond the abilities of a simple XMPP client.

9. IANA Considerations

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

10. XMPP Registrar Considerations



Appendix A: Document Information

XMPP Standards Foundation
Last Updated
Approving Body
XMPP Council
XEP-0071, XEP-0393, XEP-0394
Superseded By
Short Name
Source Control

This document in other formats: XML  PDF

Appendix B: Author Information

Georg Lukas


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. XEP-0393: Message Styling <https://xmpp.org/extensions/xep-0393.html>.

3. XEP-0394: Message Markup <https://xmpp.org/extensions/xep-0394.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 1.0.0 (2021-04-01)
    Initial published version.
    XEP Editor (jsc)
  2. Version 0.0.1 (2021-04-01)

    First draft.


Appendix I: Bib(La)TeX Entry

  title = {Message Fancying},
  author = {Lukas, Georg},
  type = {XEP},
  number = {0457},
  version = {1.0.0},
  institution = {XMPP Standards Foundation},
  url = {https://xmpp.org/extensions/xep-0457.html},
  date = {2021-04-01/2021-04-01},