HTTP/2 200 date: Mon, 14 Jul 2025 19:22:00 GMT content-type: text/plain; charset=utf-8 content-length: 10684 cf-ray: 95f362e3dbd8f4df-BLR last-modified: Fri, 16 Dec 2016 15:30:52 GMT etag: "19116-543c8415b5182-gzip" vary: Accept-Encoding content-encoding: gzip strict-transport-security: max-age=31536000; includeSubDomains x-frame-options: SAMEORIGIN x-xss-protection: 1; mode=block x-content-type-options: nosniff cache-control: max-age=1200 cf-cache-status: HIT accept-ranges: bytes server: cloudflare alt-svc: h3=":443"; ma=86400 Internet Architecture Board (IAB) N. Brownlee Request for Comments: 7996 The University of Auckland Category: Informational December 2016 ISSN: 2070-1721 SVG Drawings for RFCs: SVG 1.2 RFC Abstract This document specifies SVG 1.2 RFC -- an SVG profile for use in diagrams that may appear in RFCs -- and considers some of the issues concerning the creation and use of such diagrams. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Architecture Board (IAB) and represents information that the IAB has deemed valuable to provide for permanent record. It represents the consensus of the Internet Architecture Board (IAB). Documents approved for publication by the IAB are not a candidate for any level of Internet Standard; see Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc7996. Copyright Notice Copyright (c) 2016 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 (https://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. Brownlee Informational [Page 1]  RFC 7996 SVG Drawings for RFCs: SVG 1.2 RFC December 2016 Table of Contents 1. Introduction ....................................................2 2. SVG 1.2 RFC: An SVG Profile for RFCs ............................3 2.1. Elements, Properties, and Attributes Allowed in SVG 1.2 RFC ................................................4 3. How to Create SVG Drawings ......................................7 4. Accessibility Considerations ....................................7 5. Examples of Diagrams Common in RFCs .............................8 5.1. Packet Layout Diagrams .....................................8 5.2. Sequence Diagrams (1) ......................................8 5.3. Sequence Diagrams (2) ......................................8 6. Security Considerations .........................................8 7. References ......................................................9 7.1. Normative References .......................................9 7.2. Informative References .....................................9 Appendix A. RELAX NG Compact (RNC) Schema for SVG 1.2 RFC .........11 IAB Members at the Time of Approval ...............................53 Acknowledgements ..................................................53 Author's Address ..................................................53 1. Introduction Over the last few years, the RFC Editor has worked with the Internet community to develop specifications for changes in the format of RFCs. An outline of the resulting specifications was published as [RFC6949] in May 2013. Since then, a Design Team has been working with the RFC Editor to flesh out those specifications. One aspect of the changes is to allow line drawings in RFCs; [RFC6949] says Graphics may include ASCII art and a more complex form to be defined, such as SVG line art [SVG]. Color and grayscale will not be accepted. RFCs must correctly display in monochromatic black- and-white to allow for monochrome displays, black-and-white printing, and support for visual disabilities. SVG (Scalable Vector Graphics) has been developed by W3C, the World Wide Web Consortium; its current standard is SVG 1.1 Full [W3C.REC-SVG11-20110816]. This document defines SVG 1.2 RFC, an SVG profile (i.e., a subset of SVG) that is suitable for RFC line drawings. Note that in RFCs, the text provides normative descriptions of protocols, systems, etc. Diagrams may be used to help explain concepts more clearly, but they provide supporting details and should not be considered to be complete specifications in themselves. Brownlee Informational [Page 2]  RFC 7996 SVG Drawings for RFCs: SVG 1.2 RFC December 2016 The details (particularly any vocabularies) described in this document are expected to change based on experience gained in implementing the new publication toolsets. Revised documents will be published capturing those changes as the toolsets are completed. Other implementers must not expect those changes to remain backwards- compatible with the details described in this document. 2. SVG 1.2 RFC: An SVG Profile for RFCs As a starting point for SVG 1.2 RFC, the Design Team decided to use SVG Tiny 1.2 (also referred to as "SVG 1.2 Tiny") [W3C.REC-SVGTiny12-20081222]. SVG 1.2 Tiny is an SVG subset intended to be implemented on small, mobile devices such as cell phones and smartphones. That should allow RFCs to be rendered well on such devices, especially those that have small screens. However, RFCs are self-contained documents that do not change once they are published. The use of SVG drawings in RFCs is intended to allow authors to create drawings that are simple to produce and are easier to understand than our traditional "ASCII art" ones. In short, we are also trying to improve access to the content in RFCs, so SVG drawings need to be kept as simple as possible. Appendix A (below) provides a complete RELAX NG Compact (RNC) schema [RNG-HOME] for SVG 1.2 RFC. It is derived from the SVG 1.2 schema, and is the formal definition of SVG 1.2 RFC. The remainder of this section gives a simplified -- i.e., easier to read and understand -- overview of SVG 1.2 RFC. SVG can provide a complete User Interface, but within RFCs, all we need are simple diagrams that do not change once the RFC is published. Therefore, SVG 1.2 RFC does not allow anything from the following sections in SVG Tiny 1.2 [W3C.REC-SVGTiny12-20081222]: 12 Multimedia 13 Interactivity 15 Scripting 16 Animation 18 Metadata 19 Extensibility Note that SVG Tiny 1.2 elements may have many properties or attributes that are needed to support aspects of the above sections. Those are not allowed in SVG 1.2 RFC. Brownlee Informational [Page 3]  RFC 7996 SVG Drawings for RFCs: SVG 1.2 RFC December 2016 We now consider these other sections in SVG Tiny 1.2 [W3C.REC-SVGTiny12-20081222]: 9 Basic Shapes 10 Text Everything in this section is allowed in SVG 1.2 RFC. 11 Painting: Filling, Stroking, Colors and Paint Servers Anything relating to 'color' is not allowed in SVG 1.2 RFC; everything else is allowed. This is a requirement documented in [RFC6949]. 14 Linking SVG Tiny 1.2 allows Internationalized Resource Identifiers (IRIs) in references. In SVG 1.2 RFC, such links must be ASCII only. That should not cause problems, since one can just use the URI form of any IRI. Authors should try to use links only to URIs that are long-term stable. 17 Fonts SVG 1.2 RFC only allows 'serif', 'sans-serif', and 'monospace' generic font families from the WebFonts facility, described in Section 15 ("Fonts") of the W3C Cascading Style Sheets (CSS) 2.1 document [W3C.REC-CSS2-20110607]. In particular, the SVG 'font' element is not allowed. 2.1. Elements, Properties, and Attributes Allowed in SVG 1.2 RFC This section discusses elements, properties, and attributes selected for SVG 1.2 RFC from [W3C.REC-SVGTiny12-20081222]. In the list below, elements and properties are listed on the left, and their allowed values are given in parentheses on the right. is the list of allowed colors, a black-and-white subset of the SVG color names.