Network Working Group N. Brownlee Internet-Draft The University of Auckland Intended status: Informational IAB Expires: April 18, 2016 October 16, 2015 SVG Drawings for RFCs: SVG 1.2 RFC draft-brownlee-svg-rfc-13 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 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 April 18, 2016. Copyright Notice Copyright (c) 2015 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 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. Brownlee & IAB Expires April 18, 2016 [Page 1] Internet-Draft SVG Drawings for RFCs: SVG 1.2 RFC October 2015 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 . . . . . . . . . . . . . . . . . 6 4. Accessibility Considerations . . . . . . . . . . . . . . . . 7 5. Meta-language for diagrams common in RFCs . . . . . . . . . . 8 5.1. Packet Layout Diagrams . . . . . . . . . . . . . . . . . 8 5.2. Sequence Diagrams (1) . . . . . . . . . . . . . . . . . . 9 5.3. Sequence Diagrams (2) . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 8. Revision History [RFC Editor please delete] . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . 16 Appendix A. RELAX NG Compact (rnc) Schema for SVG 1.2 RFC . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 58 1. Introduction Over the last two 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 detail, and should not be considered to be complete specifications in themselves. Brownlee & IAB Expires April 18, 2016 [Page 2] Internet-Draft SVG Drawings for RFCs: SVG 1.2 RFC October 2015 The details (particularly any vocabularies) described in this document are expected to change based on experience gained in implementing the RFC production center's toolset. Revised documents will be published capturing those changes as the toolset is completed. Other implementors 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 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 cellphones 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 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. 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 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. Considering the other sections in SVG Tiny 1.2 [W3C.REC-SVGTiny12-20081222]: 9 Basic Shapes 10 Text Everything in these sections is allowed in SVG 1.2 RFC. 11 Painting: Filling, Stroking, Colors and Paint Servers Brownlee & IAB Expires April 18, 2016 [Page 3] Internet-Draft SVG Drawings for RFCs: SVG 1.2 RFC October 2015 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 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 CSS 2.1, [W3C.REC-CSS2-20110607], section 15, Fonts. In particular, the SVG 'font' element is not allowed. 2.1. Elements, properties and attributes allowed in SVG 1.2 RFC 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.