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Brownlee (Ed.) 3 Internet-Draft The University of Auckland 4 Intended status: Informational IAB 5 Expires: August 2, 2014 6 January 29, 2014 8 SVG Drawings for RFCs: SVG 1.2 RFC 9 draft-brownlee-svg-rfc-00 11 Abstract 13 This document specifies SVG 1.2 RFC - an SVG profile for use in 14 diagrams that may appear in RFCs - and considers some of the issues 15 concerning the creation and use of such diagrams. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on August 2, 2014. 34 Copyright Notice 36 Copyright (c) 2014 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 2. SVG 1.2 RFC: An SVG profile for RFCs . . . . . . . . . . . . 3 53 3. How to create SVG drawings . . . . . . . . . . . . . . . . . 4 54 4. Meta-language for diagrams common in RFCs . . . . . . . . . . 4 55 4.1. State Diagrams . . . . . . . . . . . . . . . . . . . . . 4 56 4.2. Sequence Digrgams . . . . . . . . . . . . . . . . . . . . 4 57 4.3. Packet Layout Diarrams . . . . . . . . . . . . . . . . . 4 58 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 59 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 60 7. Revision History [RFC Editor please delete] . . . . . . . . . 4 61 8. Appendix: Elements and attributes allowed in SVG 1.2 RFC . . 5 62 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 63 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 64 9.2. Informative References . . . . . . . . . . . . . . . . . 5 66 1. Introduction 68 Over the last two years the RFC Editor has worked with the Internet 69 community to develop specifications for changes in the format of 70 RFCs. An outline of the resulting specifications was published as 71 [RFC6949] in May 2013. Since then a Design Team has been working 72 with the RFC Editor to flesh out those specifications. One aspect of 73 the changes is to allow line drawings in RFCs; [RFC6949] says 75 "Graphics may include ASCII art and a more complex form to be 76 defined, such as SVG line art [SVG]. Color and grayscale will not 77 be accepted. RFCs must correctly display in monochromatic black- 78 and-white to allow for monochrome displays, black-and- white 79 printing, and support for visual disabilities." 81 SVG (Scalable Vector Graphics) has been developed by W3C, the World 82 Wide Web Consortium; its current standard is SVG 1.1 Full 83 [W3C.REC-SVG11-20110816]. This document defines SVG 1.2 RFC, an SVG 84 profile (i.e. a subset of SVG) that is suitable for RFC line 85 drawings. 87 Note that in RFCs, the text provides normative descriptions of 88 protocols, systems, etc. Diagrams may be used to help explain 89 concepts more clearly, but they are informative, not normative. 91 RFCs will be published in new formats such as http, pdf and epub, as 92 well as the traditional text format. As well as providing diagrams 93 in SVG, authors may also provide ASCII art versions for use in the 94 text version. 96 2. SVG 1.2 RFC: An SVG profile for RFCs 98 As a starting point for SVG 1.2 RFC, the Design Team decided to use 99 SVG 1.2 Tiny [W3C.REC-SVGTiny12-20081222]. SVG 1.2 Tiny is an SVG 100 subset intended to be implemented on small, mobile devices such as 101 cellphones and smartphones. That should allow RFCs to be rendered 102 well on such devices, especially those that have small screens. 103 However, RFCs are self-contained documents that do not change once 104 they are published. The use of SVG drawings in RFCs is intended to 105 allow authors to create drawings that are simple to produce, and 106 easier to understand than our traditional 'ASCII Art' ones. In 107 short, we are also trying to improve access to the content in RFCs, 108 so SVG drawings need to be kept as simple as possible. 110 SVG can provide a complete User Interface, but within RFCs, all we 111 need are simple diagrams that do not change once the RFC is 112 published. Therefore, SVG RFC does not allow anything from the 113 following sections in SVG Tiny 1.2 [W3C.REC-SVGTiny12-20081222]: 115 12 Multimedia 116 13 Interactivity 117 15 Scripting 118 16 Animation 119 18 Metadata 120 19 Extensibility 122 Considering the other sections in SVG Tiny 1.2 123 [W3C.REC-SVGTiny12-20081222]: 125 9 Basic Shapes 126 10 Text 127 Everything in these sections is allowed in SVG 1.2 RFC. 129 11 Painting: Filling, Stroking, Colors and Paint Servers 130 Anything relating to 'color' is not allowed in SVG 1.2 RFC, 131 everything else is allowed. 133 14 Linking 134 Linking is allowed in SVG 1.2 RFC, but only to components within 135 the same RFC. 136 [Suggestion: SVG Tiny 1.2 allows internationalized IRIs in 137 references. We could allow links to any document, but limit 138 such links to be ASCII only. That should not cause 139 problems,since one can just use the URI form of any IRI.] 141 17 Fonts 142 SVG 1.2 RFC only allows 'serif', 'sans-serif' and 'monospace' 143 generic font families from the WebFonts facility, described in 144 CSS 2.1 [W3C.REC-CSS2-20110607], section 15, Fonts. In 145 particular, the SVG 'font' element is not allowed. 147 3. How to create SVG drawings 149 Many drawing packages can be used to create SVG drawings, for example 150 Open Source packages Inkscape and Dia. Be aware that such packages 151 may use SVG elements or attributes that are not allowed in SVG 1.2 152 RFC. For example, the 'marker' attribute is often used to place 153 symbols such as arrowheads on lines, but 'marker' is not allowed in 154 SVG 1.2 Tiny or SVG 1.2 RFC. In such cases one has to draw the 155 arrowhead in another, simpler way. 157 [We will need to provide a tools to check that a diagram only uses 158 elements and attributes that are allowed in SVG 1.2 RFC. These are 159 listed in the Appendix below.] [Diagrams produced with these 160 packages may produce large SVG files that are hard to read or 161 understand directly. Perhaps we could provide a tool to strip out 162 unnecccessary attributes?] 164 Another way to create SVG drawings is to write programs to draw them. 165 For example, using python and its svgwrite module is a pleasant 166 environment (for those who like writing code). 168 4. Meta-language for diagrams common in RFCs 170 4.1. State Diagrams 172 4.2. Sequence Digrgams 174 4.3. Packet Layout Diarrams 176 5. IANA Considerations 178 This document does not create a new registry nor does it register any 179 values in existing registries; no IANA action is required. 181 6. Acknowledgements 183 Thanks to the Design Team members for their helpful comments and 184 suggestions for SVG 1.2 RFC. 186 7. Revision History [RFC Editor please delete] 188 version -00, 29 Jan 14: 189 Initial version, using content from Nevil's 190 emails to the Design Team. 192 8. Appendix: Elements and attributes allowed in SVG 1.2 RFC 194 9. References 196 9.1. Normative References 198 [RFC6949] Flanagan, H. and N. Brownlee, "RFC Series Format 199 Requirements and Future Development", RFC 6949, May 2013. 201 [W3C.REC-SVGTiny12-20081222] 202 Grasso, A., Ferraiolo, J., Neumann, A., Jackson, D., 203 Berjon, R., Schepers, D., Lilley, C., McCormack, C., 204 Hardy, V., Emmons, A., Hayman, S., Dahlstroem, E., 205 Shellshear, A., Ramani, N., Northway, C., Andersson, O., 206 and A. Quint, "Scalable Vector Graphics (SVG) Tiny 1.2 207 Specification", World Wide Web Consortium Recommendation 208 REC-SVGTiny12-20081222, December 2008, 209 . 211 [W3C.REC-CSS2-20110607] 212 Celik, T., Hickson, I., Bos, B., and H. Lie, "Cascading 213 Style Sheets Level 2 Revision 1 (CSS 2.1) Specification", 214 World Wide Web Consortium Recommendation REC- 215 CSS2-20110607, June 2011, 216 . 218 9.2. Informative References 220 [W3C.REC-SVG11-20110816] 221 Lilley, C., McCormack, C., Dengler, P., Grasso, A., Watt, 222 J., Ferraiolo, J., Dahlstroem, E., Jun, F., Jackson, D., 223 and D. Schepers, "Scalable Vector Graphics (SVG) 1.1 224 (Second Edition)", World Wide Web Consortium 225 Recommendation REC-SVG11-20110816, August 2011, 226 . 228 Authors' Addresses 230 Nevil Brownlee 231 The University of Auckland 233 EMail: n.brownlee@auckland.ac.nz 235 Internet Architecture Board 237 EMail: iab@iab.org