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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 draft-iab-svg-rfc

Network Working Group                                        N. Brownlee
Internet-Draft                                The University of Auckland
Intended status: Informational                                       IAB
Expires: April 2, 2015
                                                      September 29, 2014


                   SVG Drawings for RFCs: SVG 1.2 RFC
                       draft-brownlee-svg-rfc-08

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 2, 2015.

Copyright Notice

   Copyright (c) 2014 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
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   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.




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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  . . . . . . . . . . . . . . . .   6
   5.  Meta-language for diagrams common in RFCs . . . . . . . . . .   7
     5.1.  Packet Layout Diagrams  . . . . . . . . . . . . . . . . .   7
     5.2.  Sequence Diagrams (1) . . . . . . . . . . . . . . . . . .   8
     5.3.  Sequence Diagrams (2) . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   8.  Revision History [RFC Editor please delete] . . . . . . . . .  13
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

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.






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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
        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.



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   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.
 <color>, the list of allowed colours, is a black-and-white
 subset of  the SVG colour names.

 Elements:

   svg              (version, baseProfile=tiny, width, viewBox,
                     preserveAspectRatio, snapshotTime, height,
                     id, role)
   g                (id, role, transform, label,class)
   defs             (id, role)
   title            (id, role)
   desc             (id, role)
   use              (x, y, href, xlink:href, id, role, transform)

   rect             (x, y, width, height, rx, ry
                     id, role, transform, stroke-miterlimit)
   circle           (cx, cy, r, id, role, transform)
   ellipse          (cx, cy, rx, ry, id, role, transform)
   line             (x1, y1, x2, y2, id, role, transform)
   polyline         (points, id, role, transform)
   polygon          (points, id, role, transform)

   text             (x, y, rotate, id, role, transform)
   tspan            (id, role)
   textArea         (x, y, width, height, auto, id, role, transform)
   tbreak           (id, role)

   solidColor       (id, role)
   linearGradient   (gradientUnits, x1, y1, x2, y2, id, role)
   radialGradient   (gradientUnits, cx, cy, r, id, role)
   stop             (offset, id, role)
   path             (d, pathLength, id, role, transform, stroke-miterlimit)

 Properties:  (most allow inherit as a value)



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   stroke
   stroke-width
   stroke-linecap   (butt, round, square)
   stroke-linejoin  (miter, round, bevel)
   stroke-mitrelimit
   stroke-dasharray
   stroke-dashoffset
   stroke-opacity
   vector-effect    (non-scaling-stroke, none)
   viewport-fill    (none, currentColor)
   viewport-fill-opacity

   display          (inline, block, list-item, run-in, compact,
                      marker, table, inline-table, table-row-group,
                      table-header-group, table-footer-group,
                      table-row, table-column-group,
                  table-column, table-cell, table-caption,
                      none)
   visibility       (visible, hidden, collapse)
   color-rendering  (auto, optimizeSpeed, optimizeQuality)
   shape-rendering  (auto, optimizeSpeed, crispEdges,
              geometricPrecision)
   text-rendering   (auto, optimizeSpeed, optimizeLegibility,
              geometricPrecision)
   buffered-rendering  (auto, dynamic, static)

   <color>   (black, grey, darkgrey, dimgrey, lightgrey,
           gray, darkgray, dimgray, lightgray, white)
   opacity
   solid-opacity
   solid-color    (currentColor, <color>)
   color          (currentColor, <color>)

   stop-color     (currentColor, <color>)
   stop-opacity

   line-increment (auto)
   text-align     (start,end, center)
   display-align  (auto, before, center, after)

   font-size
   font-family    (serif, sans-serif, monospace)
   font-weight    (normal, bold, bolder, lighter)
   font-style     (normal, italic, oblique)
   font-variant   (normal, small-caps)
   direction      (ltr, rtl)
   unicode-bidi   (normal, embed, bidi-override)
   text-anchor    (start, middle, end)



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   fill           (none, black or grey)
   fill-rule      (nonzero, evenodd)
   fill-opacity

3.  How to create SVG drawings

   Many drawing packages can be used to create SVG drawings, for example
   Open Source packages Inkscape and Dia.  Be aware that such packages
   may use SVG elements or attributes that are not allowed in SVG 1.2
   RFC.

   -For example, the 'marker' attribute is often used to place symbols
    such as arrowheads on lines, but 'marker' is not allowed in SVG 1.2
    Tiny or SVG 1.2 RFC.  In such cases one has to draw the arrowhead in
    another, simpler way.

   -SVG clip paths are used to define a shape; objects outside that
    shape become invisible.  The 'clipPath' element is not allowed in
    SVG 1.2 Tiny or SVG 1.2 RFC.

   Diagrams produced with these packages may contain elements, their
   attributes or properties, or values of attributes or properties that
   are not allowed in SVG 1.2 RFC.  We will need to provide a tool to
   strip out anything that is not allowed in SVG 1.2 RFC, or to replace
   disallowed values, e.g. 'sans-serif' for 'Sans' as values for 'font-
   family'.  Experience with a simple test version a tool for this has
   shown that such deletion and replacement can be effective for making
   SVG files from drawing packages conform to SVG 1.2 RFC, without
   visibly changing the diagrams they produce.

   The tool described above can also be used by Authors simply to check
   that their diagrams conform to SVG 1.2 RFC.  To help with this, if
   visible changes do occur, the tool should produce a list of non-
   allowed keywords and the context in which they were found.

   Another way to create SVG drawings is to write programs to draw them.
   For example, using python and its svgwrite module is a pleasant
   environment (for those who like writing code).

   To include a diagram into an RFC, the xml2rfc (v3) tool will need to
   provide a way to include SVG drawings in Internet Drafts.

4.  Accessibility Considerations

   One of the long-term goals for RFCs is to make them more accessible,
   e.g. to sight-impaired readers.  For diagrams, it would be useful for
   authors to provide alternative forms of the diagram, so that voice-




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   reading software could be used to 'talk through' the diagram.  Simply
   reading the SVG code for a complex diagram seems unlikely to work.

   SVG 1.2 RFC allows SVG's 'title' and 'desc' elements.  'title'
   provides a brief text caption for an SVG object (much like a figure
   caption), and 'desc' provides a longer text description of what the
   object actually represents.  As well, the SVG 'role' attribute can be
   used to indicate to a browser how an SVG object is to be interpreted.
   Good suggestions on how to use these elements are given in
   [SVG-ACCESS-TIPS].

   ARIA is a W3C Recommendation for using SVG to create 'Accessible Rich
   Internet Applications.'  A helpful introduction to ARIA is provided
   by [SVG-ARIA-PRIMER], while [SVG-USING-ARIA] gives examples of how to
   use ARIA to enhance SVG accessibility.

5.  Meta-language for diagrams common in RFCs

   This section presents a few examples of possible meta-languages which
   could be used to create the kinds of diagrams that are most common in
   RFCs.  Note that they are merely examples, they do not imply that
   these particular experimental languages might be more widely
   implemented or used.  Instead, they seem to show that designing meta-
   languages simple enough to serve as audible representations of
   complex diagrams is difficult indeed!

   The SVG diagrams produced from the following examples can be seen at
   https://www.cs.auckland.ac.nz/~nevil/SVG_RFC_1.2
   along with an html version of this draft that includes the SVG
   diagrams.

5.1.  Packet Layout Diagrams

   Example: Figure 3 from RFC 793.

   In these examples the first line specifies the generated SVG
   filename.  The scale factor determines the size of the SVG drawing;
   it needs to be set so that the drawing fits nicely into the final
   document.

   'packet;' starts the packet description; it's followed by a
   description of the fields in each row.









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   info;
     output "tcp-header.svg", scale 0.65;

   packet;
     row 0;
       field "Source Port", 0 to 15;
       field "Destination Port", 16 to 31;
     row 1;
       field "Sequence Number", 0 to 31;
     row 2;
       field "Acknowledgement Number", 0 to 31;
     row 3;
       field "Data Offset", 0 to 3;
       field "Reserved", 4 to 9;
       field "Urg", 10 to 10, fsize 14;  # 14 px font so the flags fit
       field "Ack", 11 to 11, fsize 14;
       field "Psh", 12 to 12, fsize 14;
       field "Rst", 13 to 13, fsize 14;
       field "Syn", 14 to 14, fsize 14;
       field "Fin", 15 to 15, fsize 14;
       field "Window", 16 to 31;
     row 4;
       field "Checksum", 0 to 15;
       field "Urgent Pointer", 16 to 31;
     row 5;
       field "Options", 0 to 23;
       field "Padding", 24 to 31;
     row 6;
       field "Data", 0 to 31;

5.2.  Sequence Diagrams (1)

   Example: Figure 6 from draft-loreto-httpbis-trusted-proxy20-00.

   In this example, columns are vertical lines with a text header above
   them.  There are three columns, and columns 1 and 2 are spaced 250
   pixels apart.

   The rest of the file describes objects to be drawn; most of them are
   plines (polylines) from one column to another, but object 3 only
   extends across to 0.3 of the distance between columns 1 and 2.

   info;
     output "httpbis-proxy20-fig6.svg", scale 0.9;

   #Thu, 30 Jan 14 (NZDT)

   #Figure 6 of draft-loreto-httpbis-trusted-proxy20-00.txt



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   column 1 width 250;  # columns have vertical line to bottom
     text above "user-agent";

   column 2 width 250;
     text "Proxy";

   column 3; # Last col
     text "Server";

   object 1;  # Only need polylines
     pline 1 to 2, arrowhead at end;
     text above "(1) TLS ClientHello";
     text below "(ALPN ProtocolName: http)";

   object 2;
     pline 1 to 2, arrowhead at start;
     text above "(2) TLS Error";
     text below "(Proxy Cert)";

   object 3;
     pline 1 to 1.3, down, back to 1, arrowhead at end;
     text seg 2 centre "(inform user of the SecureProxy)";

   object 4;
     pline 1 to 2, arrowhead at end;
     text above "(3) TLS ClientHello";

   object 5;
     pline 1 to 2, arrowhead at start;
     text above "(4) ServerHello";

   object 6;
     blank 1 to 2;

   object 7;
     block 1 to 2, objects 8 to 15, colour "grey";
     text above "HTTP2.0";

   object 8;
     pline 1 to 2, arrowhead at end;
     text seg 1 centre "(5) stream(X) GET";

   object 9;
     pline 2 to 3, arrowhead at end;
     text seg 1 above "(6) TLS ClientHello";

   object 10;
     pline 2 to 3, arrowhead at start;



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     text seg 1 above "TLS ServerHello";

   object 11;
     blank 2 to 3;

   object 12;
     block 2 to 3, objects 13 to 15, colour "grey";
     text seg 1 above "HTTP2.0";

   object 13;
     pline 2 to 3, arrowhead at end;
     text seg 1 centre "(7) stream(Z) GET";

   object 14;
     pline 2 to 3, arrowhead at start;
     text seg 1 centre "(8) stream(Z) 200 OK";

   object 15;
     pline 1 to 2, arrowhead at start;
     text seg 1 centre "(9) stream(X) 200 OK";

5.3.  Sequence Diagrams (2)

   Example: Figure 3 from RFC 4321

   This example uses (x,y) coordinates to specify points in in plines.
   For these, the x units are columns and the y units are lines
   (positive means 'down the diagram').

   both x and y may be absolute, e.g. 4.3, or relative, e.g.  +1.5).
   For the first point of a pline, relative means 'relative to the
   starting point of the previous pline,' for other points in a pline it
   means 'relative to the last point.'

   Note that column 1 is drawn in white, i.e. nothing is drawn for it.
   It's simply used to make a blank area where objects 8 and 9 can place
   text.  For both those objects a pline is used to specify the text's
   position.

   Last, the metalanguage allows simple macros, introduced by 'define
   foo = '.  These make it easier to re-use definitions, for example of
   line types.

   info;
     output "rfc4321-fig3.svg", scale 0.9;

   # Sat,  5 Apr 14 (NZDT)




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   #Figure 3 of RFC 4321

   define hw = width 110;  # Hop width

   column 1 width 130, colour "white";  # No heading or vertical line

   column 2 hw;  text above "UAC";

   column 3 hw;  text "P1";

   column 4 hw;  text "P2";

   column 5 hw;  text "P3";

   column 6 hw;  text "UAS";

   define tgrey = colour "lightgrey" width 5;  # Thick grey
   define ahe = arrowhead at end;

   object 1;
     pline 1.8
       to 2.3 tgrey, to (2.4,+0), to (2.6,+1.5), to (2.7,+0) ahe,
       to 3.3 tgrey, to (3.4,+0), to (3.6,+1.5), to (3.7,+0) ahe,
       to 4.3 tgrey, to (4.4,+0), to (4.6,+1.5), to (4.7,+0) ahe,
       to 5.3 tgrey, to (5.4,+0), to (5.6,+1.5), to (5.7,+0) ahe,
       to 6.3 tgrey;

   object 2;
     pline (1.8,+10) to 2.3 tgrey;

   object 3;
     pline (3.3,+2)
       to 2.85 tgrey, to (2.7,+0) tgrey,
       to (2.5,+0), to (2.25,+1.5), to (2.0,+0) ahe;
     text seg 2 centre "408";

   object 4;
     pline (4.3,+1.5)
       to 3.9 tgrey, to (3.7,+0) tgrey,
       to (3.5,+0), to (3.3,+1.5), to (3.1,+0) ahe,
       to 2.9 tgrey, to (2.7,+0) tgrey,
       to (2.5,+0), to (2.25,+1.5), to (2.0,+0) ahe;
     text seg 2 centre "408";
     text seg 7 centre "408";

   object 5;
     pline (5.3,+1.5)
       to 4.9 tgrey, to (4.7,+0) tgrey,



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       to (4.5,+0), to (4.3,+1.5), to (4.1,+0) ahe,
       to 3.9 tgrey, to (3.7,+0) tgrey,
       to (3.5,+0), to (3.3,+1.5), to (3.1,+0) ahe,
       to 2.9 tgrey, to (2.7,+0) tgrey,
       to (2.5,+0), to (2.25,+1.5), to (2.0,+0) ahe;
     text seg  2 centre "408";
     text seg  7 centre "408";
     text seg 12 centre "408";

   object 6;
     pline (6.3,+1.5)
       to 5.9 tgrey, to (5.7,+0) tgrey,
       to (5.5,+0), to (5.3,+1.5), to (5.1,+0) ahe;
       to 4.9 tgrey, to (4.7,+0) tgrey,
       to (4.5,+0), to (4.3,+1.5), to (4.1,+0) ahe;
       to 3.9 tgrey, to (3.7,+0) tgrey,
       to (3.5,+0), to (3.3,+1.5), to (3.1,+0) ahe;
       to 2.9 tgrey, to (2.7,+0) tgrey,
       to (2.5,+0), to (2.25,+1.5), to (2.0,+0) ahe;
     text seg  2 centre "408";
     text seg  7 centre "408";
     text seg 12 centre "408";
     text seg 17 centre "408";

   object 7:
     pline (1.63,4.1) to (1.73,+0);

   object 8;
     pline (1.68,4.1) to (+0,14) arrowhead at end;
     text centre "64*T1";

   object 9;
     pline (1.2,13.1) to (1.5,+0) colour "white";
     text centre "(timeout)";

6.  IANA Considerations

   This document does not create a new registry nor does it register any
   values in existing registries; no IANA action is required.

7.  Acknowledgements

   Thanks to the RSE and the Design Team members for their helpful
   comments and suggestions for SVG 1.2 RFC.







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8.  Revision History [RFC Editor please delete]

   version -08, 29 Seo 14:
      Section 1: Changed comment about diagrams 'not being normative' to
      'not complete specifications in themselves.
      Section 2.1: Added SVG 1.2 Tiny 'id' attribute because most
      drawing packages use it in constructing drawings.
      Section 2.1: Added SVG 1.2 Tiny 'role' attribute so that ARIA can
      use it.
      Section 3: added comment about changes to xml2rfc required to
      include SVG diagrams.
      Section 4: Added reference to svg-aria-primer.

   version -07, 3 Jul 14:
      Expanded text about Accessibility in 'how to create SVG drawings'
      section into 'Accessibility Considerations section.  Added two SVG
      Accessibility references to support that.

   version -06, 26 Jun 14:
      Remove trailing / from URL in section 4; the html version on
      tools.ietf.org/html assumed the next word was part of that URL.

   version -05, 25 Jun 14:
      Improved section on 'how to create SVG drawings' By adding some
      text about which elements aren't allowed in SVG 1.2 RFC.
      Added more text describing the tool for checking, stripping out or
      replacing incompatible elements and attributes from an SVG file.

   version -04, 30 Apr 14:
      Fixed typos, used full references for two of the w3c refs - each
      had an author name using UTF8 characters.
      Moved the Elements and Attributes appendix up earlier to make it
      sub-section 2.1.
      Disclaimer added to the Meta-languages section.

   version -03, 14 Apr 14:
      Added two more example diagrams; a simple packet layout, and a
      diagram that uses lots of diagonal lines.

   version -02, 12 Feb 14:
      Added metalanguage example to make time-sequence drawings.

   version -01, 11 Feb 14:
      Allow links to 'long-term stable URIs'
      Link URIs must be ASCII only
      Need for tools to check SVG 1.2 RFC compatibility and to strip
      'unnecessary' attributes explicitly stated.




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      Statement that drawings can't be normative removed; Postscript-
      only RFCs already exist.
      Added most attributes and elements to the Appendix.

   version -00, 29 Jan 14:
      Initial version, using content from Nevil's
      emails to the Design Team.

9.  References

9.1.  Normative References

   [RFC6949]  Flanagan, H. and N. Brownlee, "RFC Series Format
              Requirements and Future Development", RFC 6949, May 2013.

   [W3C.REC-SVGTiny12-20081222]
              Andersson, O., Berjon, R., Dahlstrom, E., Emmons, A.,
              Ferraiolo, J., Grasso, A., Hardy, V., Hayman, S., Jackson,
              D., Lilley, C., McCormack, C., Neumann, A., Northway, C.,
              Quint, A., Ramani, N., Schepers, D., and A. Shellshear,
              "Scalable Vector Graphics (SVG) Tiny 1.2 Specification",
              World Wide Web Consortium Recommendation REC-
              SVGTiny12-20081222, December 2008,
              <http://www.w3.org/TR/2008/REC-SVGTiny12-20081222>.

   [W3C.REC-CSS2-20110607]
              Bos, B., Celik, T., Hickson, I., and H. Lie, "Cascading
              Style Sheets Level 2 Revision 1 (CSS 2.1) Specification",
              World Wide Web Consortium Recommendation REC-
              CSS2-20110607, June 2011,
              <http://www.w3.org/TR/2011/REC-CSS2-20110607>.

9.2.  Informative References

   [W3C.REC-SVG11-20110816]
              Dahlstrom, E., Dengler, P., Grasso, A., Lilley, C.,
              McCormack, C., Schepers, D., Watt, J., Ferraiolo, J.,
              Fujisawa, J., and D. Jackson, "Scalable Vector Graphics
              (SVG) 1.1 (Second Edition)", World Wide Web Consortium
              Recommendation REC-SVG11-20110816, August 2011,
              <http://www.w3.org/TR/2011/REC-SVG11-20110816>.

   [SVG-ACCESS-TIPS]
              Watson, L., "Tips for Creating Accessible SVG", SitePoint
              tips-accessible-svg, May 2014,
              <http://www.sitepoint.com/tips-accessible-svg>.





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   [SVG-ARIA-PRIMER]
              Pappas, L., Schwerdtfeger, R., and M. Cooper, "WAI-ARIA
              1.0 Primer", World Wide Web Consortium WD WD-wai-aria-
              primer-20100916, September 2010,
              <http://www.w3.org/TR/2010/WD-wai-aria-primer-20100916>.

   [SVG-USING-ARIA]
              Watson, L., "Using ARIA to enhance SVG accessibility", The
              Paciello Group 2013/12/using-aria-enhance-svg-
              accessibility, December 2013,
              <http://blog.paciellogroup.com/2013/12/
              using-aria-enhance-svg-accessibility>.

Authors' Addresses

   Nevil Brownlee
   The University of Auckland

   Email: n.brownlee@auckland.ac.nz


   Internet Architecture Board

   Email: iab@iab.org



























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