HyperText Markup Language Request For Comments Format
draft-hildebrand-html-rfc-03
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Joe Hildebrand , Heather Flanagan | ||
| Last updated | 2014-06-06 | ||
| Replaced by | draft-iab-html-rfc, RFC 7992 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-hildebrand-html-rfc-03
Network Working Group J. Hildebrand
Internet-Draft Cisco Systems, Inc.
Intended status: Informational H. Flanagan
Expires: December 8, 2014 RFC Editor
June 6, 2014
HyperText Markup Language Request For Comments Format
draft-hildebrand-html-rfc-03
Abstract
This document defines the HTML format that should be used for the
production of Internet-Drafts and RFCs. The HTML output will include
a default CSS to enable page layout, and the HTML itself includes
semantic information only. This format will be rendered from the
canonical XML format for an RFC.
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 December 8, 2014.
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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Introduction
1.1. Background
The RFC Series has been in existence for over 40 years. During much
of that time, the limitations of character set, line and page length,
and graphics restrictions of RFC documents met the most immediate
needs of the majority of authors and readers. As technology changed,
new formats that allowed for a richer set of edit, search and display
features came in to use, and tools were created to convert the plain
ASCII documents to other desired formats such as HTML, PDF, and
Microsoft Word. While the converted versions of the RFCs are widely
available, the canonical display format remains the plain text,
ASCII, line-printer structured one.
In 2013, after a great deal of community discussion, the decision was
made to shift from the plain text, ASCII-only canonical format to XML
[I-D.hoffman-xml2rfc]. Several different publication formats will be
rendered from that canonical XML, including HTML, PDF, TXT, and EPUB.
This memo describes an HTML format that will be used as one of the
publication formats for the RFC Series. It defines a strict subset
of HTML appropriate for Internet-Draft and RFC Series documents, and
serves as a comprehensive example of all of the HTML elements that
are permissible. The CSS that defines the visual layout, while
included in the HTML file, will be described in a separate document
[W3C.REC-CSS2-20110607]. The HTML itself will represent semantic
information only.
1.2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
[RFC2119].
2. Requirements for HTML
The HTML has to render correctly on the following:
o the latest released versions of Chrome, Firefox, and IE running on
Windows 8 in November 2013
o the latest released versions of Chrome, Firefox, and Safari
running on Mac OS X 10.9 in November 2013
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o the latest released versions of Chrome and Safari running on iOS 7
in November 2013
o the latest released versions of Chrome and Firefox running on
Ubuntu 13.10 in November 2013
o the latest released versions of Chrome and Firefox running on
Android 4.1 in November 2013
These requirements are expected to change in the future to reflect
the expectation that HTML rendering will be required for current
versions of browsers and platforms, while ideally continuing to
render correctly on earlier versions.
The HTML document must preserve all semantic information that is in
the canonical XML document. One use case is that preformatted text
that has different tags in the XML will also be differentiable in the
HTML, making it trivial to extract all of the (for example) ABNF in
an RFC with a simple program. Another use case is that someone who
wants to write programs that will extract information from an RFC can
do so equally well with the XML and HTML, and can choose the tool
that uses one or the other format for input.
The HTML document must come with a default, internal set of CSS
formatting. This will allow for a mostly-consistent display of RFCs
across browsers. It will also allow for the HTML file to be moved
over different transports (such as e-mail) and have the result look
the same.
The HTML must display adequately in at least one text-based browser.
Any use of javascript must not negatively impact the ability to read
the document.
The HTML document must allow easy local override of the default CSS
formatting. This will allow users who have a different visual style
that they prefer to make RFCs display with that style without having
to alter the contents of the HTML document. This might also be
valuable for allowing people with specific accessibility needs to
have custom CSS.
No HTML tags in the document may have style information. All style
information must be done through "class" and "id" attributes, with
the style for those represented in the CSS alone. Exceptions can be
made for formatting that is not possible in any other way in HTML5
[W3C.CR-html5-20130806], such as table column widths.
The HTML must make it easy to separate chunks into separate files.
This will make creating EPUB documents easier in the future.
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The output needs to be HTML5. Language extensions might be
acceptable after further discussion. The RFC Editor will use an
automated validating tool before publishing the HTML. This
requirement is not important for viewing with browsers, but is
important for programs that will use the HTML format as input for
processing.
The HTML must not have any Javascript or other active code in
<script> or <object> tags.
All section, subsections, figures, and paragraphs should have stable
numbered link anchors. Additionally, anchors expressed in the source
XML should be exposed as anchors in the HTML as well.
The abstract must be marked up or tagged in a way that search engines
will extract it as summary.
Normative information must be easily accessible to the following
consumers:
o People with impaired vision, including those that use large fonts
and those that use screen readers
o People with difficult;y distinguishing between colors
o People who use devices with small screens, such as cell phones
o Other groups TBD
Specific instances where these goals are important in the design
choices of the format have been called out in the text.
The HTML document does not require the inclusion of non-semantic
information such as comments and processor instructions.
NOTE: designing for these consumers does not preclude the use of
features they cannot use, but does require that key semantic data is
not lost when read using the tools and settings that are required by
a given constituency.
3. HTML Format
The format specified here is a subset of HTML, deemed to be widely-
implemented by common browsers at the time that the specification was
created, likely to continue to be widely-implemented in the future,
and unlikely to cause security issues.
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3.1. Syntax
The following rules SHALL be enforced:
o The HTML source MUST be encoded as UTF-8, as specified in RFC3629.
Note that RFC3629 forbids "surrogate" codepoints in the range
U+D800 to U+DFFF.
o The document MUST be valid HTML5.
o Single quotes (U+0027 APOSTROPHE: ') MUST be used to quote
attribute values. Unquoted attribute values MUST NOT be used.
o Each logical line MUST be terminated solely with a \n (U+000A:
LINE FEED), otherwise known as "Unix-style" line endings.
o Other than \n (U+000A: LINE FEED), code points less than " "
(U+0020: SPACE) (otherwise known as "control characters") MUST NOT
be used. Any character references that would generate these code
points (e.g. ) MUST NOT be used. NOTE: this rule explicitly
forbids \t (U+0009: CHARACTER TABULATION), \f (U+000C: FORM FEED),
and \r (U+000D: CARRIAGE RETURN) from appearing in the source.
o Each text-containing element such as headings (<h1>-<h6>),
paragraphs (<p>), or list items (<li>), MUST be serialized as a
single line without wrapping.
o The contents of <pre> elements MUST NOT be modified by processing
tools. The following rules apply to all elements except for
<pre>:
* HTML SHALL be indented using spaces (not tabs).
* Each child element SHALL be indented two spaces more than its
parent element, unless the child element is mixed with non-
whitespace-only text children of the same parent element.
NOTE: none of these rules affect the rendered output of the HTML, but
are intended to increase the chance that multiple tools that process
the format will generate identical syntax. In turn, this will make
difference tools that operate on the HTML source easier to write.
3.2. Basic Structure
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3.2.1. HTML5
The HTML comprising the document MUST be valid according to the
latest version of the HTML specification at the time of publishing,
starting with the version commonly known as HTML5. Although the HTML
specification mandates several of syntax and structure rules in this
document, they are called out here for emphasis.
3.2.2. DOCTYPE
The DOCTYPE of the document MUST be "html", which declares that the
document is compliant with HTML5. The document will start with
exactly this string:
<!DOCTYPE html'>
The SYSTEM 'about:legacy-compat' portion MAY be dropped in the future
if the tooling chosen to produce this format does not require it.
3.2.3. Root Element
The root element of the document MUST be <html>. This element SHOULD
include a lang attribute, whose value is a RFC5646 language tag
describing the natural language of the document. For documents
submitted to the RFC Series or Internet-Draft Series, the language
tag MUST be 'en', meaning "English". If the lang attribute is not
present, its value should be taken to be 'en'.
3.2.4. Charset Declaration
In order to be correctly processed by browsers that load the HTML
using a mechanism that does not provide a valid MIME content-type or
charset, the HTML <head> element MUST contain a <meta> element, with
charset attribute with value 'utf-8'. This will look like:
<meta charset='utf-8' >
3.2.5. Style
The <head> SHOULD contain an embedded CSS stylesheet in a <style>
element. The styles in the stylesheet are to be set consistently
between documents by the RFC Editor, according to the best practices
of the day. The RFC Editor SHALL choose a stylesheet that does not
modify the meaning of the normative text of the document. The RFC
Editor SHALL make the stylesheet available via a standard protocol
(e.g. HTTP or HTTPS) for ease of authorship. However, when a
document is submitted, external stylesheets (other than "local.css"
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as specified below) are NOT ALLOWED. The stylesheet itself MUST NOT
be considered as normative information.
To ensure consistent formatting, individual style attributes SHOULD
NOT be used in the main portion of the document source except in
highly exceptional circumstances; each use MUST be individually
justified.
Different readers of a specification will desire different tweaks to
the stylesheet. To facilitate this, the <head> SHOULD include a
<link> to a stylesheet in the same directory as the HTML file, named
"local.css", after the embedded stylesheet. Note that this
"local.css" file will not exist for most users; browsers will
correspondingly ignore this <link>.
For example:
<head>
<style type='text/css'>
<! --
/* RFC-editor styles */
-->
</style>
<link rel='stylesheet' type='text/css' href='local.css' />
</head>
3.2.6. Emphasis
Words or phrases may be emphasized using the <em> element, usually
rendered as italics. Strong emphasis may be donated with the
<strong> element, which is usually rendered as boldface. Underlining
MUST NOT be used except for links, to avoid visual confusion. Text-
only emphasis such as "_bold_" MUST NOT be used.
The RFC Editor will set a policy that reflects the current feelings
of the community as to whether this emphasis markup is allowed in
documents that are submitted for publication in the RFC series.
3.2.7. Comments
HTML comments will not be generated by the rendering agent from the
canonical XML.
3.2.8. Sections
Each section of the document SHALL be formatted as a <div> tag, with
a class attribute with value 'section'. A document-unique id
attribute SHOULD be assigned to each section <div>.
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NOTE: HTML5 requires id attributes to be unique across an entire
document.
Each section <div> MUST contain a header tag (<h2>-<h6>) of the
appropriate depth, with top-level sections getting an <h2> tag, and
each nested section getting the next higher header level. If more
than five levels of headers are required, <h6> MUST be used for each
deeper-nested section. However, nesting sections more than five
levels deep is NOT RECOMMENDED.
The text in each header tag MUST begin with the section number.
Section numbers MUST begin at "1.", and MUST increment by one for
each successive section at the same level. Subsections MUST be
numbered by appending the subsection number to the parent section
number.
It is RECOMMENDED that the section number be wrapped in an <a>
element, whose href attribute points to the corresponding section div
with a local relative reference. This <a> element SHOULD have the
CSS class self-ref.
Within a section, each "normal" paragraph MUST be surrounded by a <p>
element.
For example:
<div class='section' id='example'>
<h2><a class='self-ref' href='#example'>1.</a>Example Section
</h2>
<p>This is a description of the example</p>
<div class='section' id='nested'>
<h3><a class='self-ref' href='#nested'>1.1.</a> Nested Section
</h3>
<p>This is a description of the nested section.</p>
<p>This is the second description paragraph.</p>
</div>
</div>
Parent sections that contain child sections MUST NOT contain "normal"
paragraphs after a sub-section. For example, the following is
invalid:
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<div class='section' id='example'>
<h2><a class='self-ref' href='#example'>1.</a> Example Section
</h2>
<p>This is a description of the example</p>
<div class='section' id='nested'>
<h3><a class='self-ref' href='#nested'>1.1.</a>Nested Section
</h3>
<p>This is a description of the nested section.</p>
</div>
<p>BAD PROSE!</p>
</div>
3.2.9. Appendices
Appendices are special cases of top-level sections. Each appendix of
the document SHALL be formatted as a <div> tag, with a class
attribute with value 'appendix'. A document-unique, id attribute
SHOULD be assigned to each section <div>. The id MAY be human-
readable or generated. Each appendix <div> MUST contain an <h2>
element containing text that describes the purpose of the appendix.
Appendices are identified to the reader with Latin capital letters
A-Z, in order. It is NOT RECOMMENDED to have more than 26
appendices, but if required, appendices "AA.", "AB.", etc. follow
Appendix Z.
Inside the appendix, subsections MUST be formatted per Sections,
numbered sequentially. For example, the first subsection of
"Appendix A." is "Appendix A.1.".
For example:
<div class='appendix' id='acknowledgements'>
<h2>Appendix A. Acknowledgements</h2>
<p>The author gratefully acknowledges the contributions of...</p>
<div class='section' id='contributors'>
<h3>Appendix A.1. Contributors</h2>
<p>These people contributed text...</p>
</div>
</div>
3.2.10. Paragraphs
Paragraphs MUST be contained in a section <div> or an appendix <div>.
A document-unique, id attribute SHOULD be assigned to each <p>. The
id will usually be machine-generated, but MAY be human-readable if
desired.
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It is RECOMMENDED that each paragraph be kept relatively small
compared to a "page" in previous RFC formats, so that references to
each paragraph are at least as valuable as page references have been
in previous formats.
3.2.11. Lists
Lists may be used inside a section <div>, and may nest in other lists
as needed. However, lists MUST NOT be nested inside a <p> element.
Unordered lists (<ul>) and ordered lists (<ol>) may both be used.
For example:
<div class='section' id='lists'>
<h4>Unordered list</h4>
<p id='lists-p-1'>An explanation:</p>
<ul>
<li>One</li>
<li>Two</li>
<ol>
<li>Two.1: (this one is numbered)</li>
</ol>
</ul>
</div>
3.2.12. References
Reference format must follow the guidance in the RFC Style Guide
[I-D.iab-styleguide].
3.2.13. Quotes
Non-trivial direct quotes from other documents SHOULD use the
<blockquote> element. If the quote needs a citation, wrap the
<blockquote> in a <figure> and add a <figcaption> element that
contains text (and possibly links) that describe the quote. For
example, this code:
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<figure>
<blockquote>
<p>Here a <code>blockquote</code> element
is used in conjunction with a <code>figure</code> element and
its <code>figcaption</code> to clearly relate a quote to its
attribution (which is not part of the quote and therefore
doesn't belong
inside the <code>blockquote</code> itself):</p>
</blockquote>
<figcaption>Sample Quote from <a class='ref' href='#w3c:
CR-html5-20130806'>HTML5</a>,
section 4.5.4</figcaption>
</figure>
Would render as:
Here a blockquote element is used in conjunction with a figure
element and its figcaption to clearly relate a quote to its
attribution (which is not part of the quote and therefore
doesn't belong inside the blockquote itself):
Figure 1: Sample Quote from HTML5, section 4.5.4
3.3. More Elaborate Information
This section describes how to format several types of information
that occur regularly in documents for the Internet-Draft and RFC
Series which are not descriptive text.
3.3.1. Requirement Keywords
The RFC2119 keywords in the document will be set off with special
markup. They MUST be surrounded with a <span> element containing the
CSS class rfc2119. For example:
They <span class='rfc2119'>MUST</span> be surrounded
3.3.2. Formatting the Table of Contents
The table of contents for the document MUST appear in a <div>
element, which SHOULD precede any of the sections of proper document
content. The <div> element MUST have an id attribute with value
'toa'. The <div> element SHOULD contain an <h2> element containing
the string Table of Contents, followed by nested <ul> and <li>
elements describing the structure of the document, with links to each
of the sections mentioned. For example:
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<div id='toc'>
<h2>Table of Contents</h2>
<ul>
<li>
<div>1. <a href='#introduction'>Introduction</a></div>
<ul>
<li>
<div>1.1. <a href='#background'>Background</a></div>
</li>
...
NOTE: the Table of Contents SHOULD NOT be considered meta-data for
the document. The sections themselves SHOULD contain all of the data
that is required.
3.3.3. SVG
SVG can be included directly in the HTML source, surrounded by a
<figure> element and succeeded by a <figcaption> element, as
described in Section . The root <svg> element MUST contain a <title>
or <desc> element that fully describes the diagram for accessibility
to screen readers; this is similar to the alt; attribute on images.
See "SVG Drawings for RFCs: SVG 1.2 RFC" for details on the
appropriate SVG profile for use in RFCs [I-D.brownlee-svg-rfc].
3.3.4. Inline Code
Use the <code> element to set aside literal references to code or
protocol elements in the middle of a paragraph. If desired, the
language of the code or protocol can be declared using a class
attribute starting with language-. For example:
Use the <code class='language-html'><;code>;</code> element
3.3.5. Blocks of Code
Larger sections of code or protocol can be included using a <pre>
element with a class attribute of code. If desired, the language of
the code or protocol can be declared using a further class value
starting with 'language-' (multiple class values are separated by
spaces in HTML). The text inside the <pre> element will be rendered
in a monospace font, with whitespace maintained. For example:
<pre class='code language-html'>
<html>
< />
</html>
</pre>
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Will be rendered as:
<html>
< />
</html>
Depending on author style, blocks of code MAY be enclosed in a
<figure> element, with a <figcaption> element that describes the
block. For example, see Figure 2.
<figure id='blockfigure'>
<pre class='code language-html'></pre>
<figcaption>A code block wrapped in a figure.</figcaption>
</figure>
</figure>
Figure 2: A code block wrapped in a figure
3.3.6. ASCII Art
ASCII art is still preferred by some authors in preference to an
image or SVG. The RFC Editor may decide to prefer SVG, or may decide
to prohibit ASCII art in the future, depending on the needs of the
community at the time of publishing. Until that time, to include
ASCII art, wrap a <pre> element with class='ascii' in a <figure>
along with a <figcaption>, as if the <pre> element were an
Section 3.3.4 image. For example:
<figure>
<pre class='ascii'>
+-----------+
| original | <+
+-----------+ |
| |
| nit | edit
v |
nit (no-op) +-----------+ |
+-------------- | | |
| | canonical | |
+-------------> | | -+
+-----------+
</pre>
<figcaption>Sample ASCII art</figcaption>
</figure>
Figure 3: Sample ASCII art
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3.3.7. Packet Formats
Packet format descriptions can be encoded as a <table> element
wrapped in a <figure> along with a <figcaption>, as if the <pre>
element were an image, as specified in Section . For consistent
formatting, the <table> element should have class pdu. For example:
<figure>
<figcaption>Sample packet format</figcaption>
<table class='pdu'> [table describing the packet] </table>
</figure>
4. Document Metadata
Metadata for the document SHOULD be easily extractable from the
document by tools that ordinarily process HTML. Typically, the class
and id attributes can be used to query the document using CSS-style
selectors. The metadata scheme SHOULD be designed such that the
element name is not required in order to select a given piece of
data. Instead, any element that can contain text can be used for a
given class or id to be selected. The value of the data contained by
the selected element(s) consists of the concatenation of all of the
text from all of the child nodes of the selected element or elements,
with each run of consecutive whitespace Unicode codepoints
[codepoints with the White_Space property, such as U+0020 (SPACE),
U+0009 (CHARACTER TABULATION), U+000A (LINE FEED), U+000C (FORM
FEED), U+000D (CARRIAGE RETURN), U+00A0 (NON-BREAKING SPACE), and
U+2029 (PARAGRAPH SEPARATOR)] compressed to a single U+0020 (SPACE).
The metadata scheme MUST allow unambiguous selection.
The id attribute is used to identify pieces of data that are
guaranteed to be unique across the document. Any element with an id
attribute can also be used as a fragment target in a URI by starting
with the base URI of the document, then appending "#" (U+0023: NUMBER
SIGN) and the value of the id attribute. In CSS, the element with a
given id attribute value is selected by prepending the value with '#'
(U+0023: NUMBER SIGN). For example, the following HTML in a document
with the URI http://example.com/index.html:
<div id='example'>Important Text</div>
Can be targeted directly with the URL http://example.com/
index.html#example, and the CSS selector #example.
The class attribute is a catch-all tagging mechanism for everything
in the document that might not be unique. Multiple classes may be
defined on a single element by setting the class attribute to a
space-separated list of classes. All of the elements with a given
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class name can be selected in CSS by prepending the class name with
"." (U+002E: FULL STOP).
4.1. Document Information
Information about the document as a whole. The <div> element with
id='document' SHOULD be the first child element of the HTML. For
example:
<div id='document'>
<div class='identifiers'>
<div class='workgroup'>Network Working Group</div>
<div class='series'>Internet-Draft</div>
<div class='status'>Standards Track</div>
<div class='published'>2012-07-07</div>
<div class='expires'>2013-01-07</div>
<div class='version'>03</div>
</div>
<div class='authors'>
<div class='author'>
<span class='initial'>J.</span>
<span class='surname'>Hildebrand</span>
<span class='company'>Cisco Systems, Inc.</span>
</div>
</div>
</div>
More details for this format will be included in future drafts of
this document.
4.2. Title
The title of the document MUST appear in an <h1> element, which
SHOULD follow directly after the Document Information. The <h1>
element MUST have an id attribute with value 'title'. For example:
<h1 id='title'>HTML RFC Format</h1>
4.3. Abstract
The abstract for the document MUST appear in a <div> element, which
SHOULD follow directly after the Title. The <div> element MUST have
an id attribute with value 'abstract'. The <div> element SHOULD
contain an <h2> element containing the word Abstract, and MUST
contain one or more <p> elements containing text that describes the
document succinctly. For example:
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<div id='abstract'>
<h2>Abstract</h2>
<p>This document defines an HTML format...</p>
</div>
4.4. IPR Statements
The IPR boilerplate for the document MUST appear in a <div> element,
which SHOULD follow directly after the Abstract. The <div> element
MUST have an id attribute with value 'ipr' and a CSS class of the
name of the relevant IPR ruleset. The only valid values for the IPR
ruleset class are trust200902, noModificationTrust200902, and
noDerivativesTrust200902 at this time. The contents of the <div>
element are to be set correctly for the given ruleset, based on
guidance from the IETF trust. For example:
<div id='ipr' class='trust200902'>
<h2>Status of this Memo</h2>
<p>...</p>
<h2>Copyright Notice</h2>
<p>...</p>
</div>
4.5. Author
This section will be augmented with normative text when an approach
is decided upon. A quick example (as an existence proof) can be
found in Figure 4.
<address class='vcard'>
<span class='n hidden'>
<span class='family-name'>Hildebrand</span>
<span class='given-name'>Joe</span>
</span>
<span class='nickname hidden'>hildjj</span>
<span class='fn'>Joe Hildebrand</span>
<span class='org'>Cisco Systems, Inc.</span>
<a class='email' href='jhildebr@cisco.com'>jhildebr@cisco.com</a>
<div class='adr'>
<div class='street-address'>1899 Wynkoop St, Suite 600</div>
<div><span class='locality'>Denver</span>,
<span class='region'>CO</span>
<span class='postal-code'>80202<span></div>
<div class='country-name'>United States</div>
</div>
</address>
Figure 4: Sample (temporary) author information
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4.6. Bibliographical Information
TBD
5. Examples
5.1. Self
This draft itself is a good example of how to use the format. Please
view-source.
5.2. Code Sample
#include \<stdio.h\>
int main(int argc, char **argv)
{
printf("Hello, IETF\n");
return 0;
}
5.3. Sequence Diagrams
Include an image tag with class='sequence', where the alt; text is
the WebSequenceDiagrams.com source for the diagram.
Before publication, this approach will be replaced by something more
well-specified and not requiring third-party software.
<figure>
<img class='sequence' alt;='
title Authentication Sequence
Alice->;Bob: Authentication Request
note right of Bob: Bob thinks about it
Bob->;Alice: Authentication Response' >
<figcaption>A sample sequence diagram</figcaption>
</figure>
title Authentication Sequence Alice->Bob: Authentication
Request note right of Bob: Bob thinks about it Bob->Alice:
Authentication Response
Figure 5: A sample sequence diagram
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5.4. ABNF
Augmented Backus-Naur Form is a way of describing formal syntax,
described in RFC5234. Include ABNF (without extra indentation) in a
<pre> element, with CSS class 'code' and "language-abnf". For
example:
<pre class='code language-abnf'>
label = top-level *4section-num
top-level = section-num / appendix-let
section-num = 1*DIGIT "."
appendix-let = 1*CAP "."
CAP = %x41-5A ; A-Z
DIGIT = %x30-39 ; 0-9
</pre>
Is rendered as:
label = top-level _4section-num top-level = section-num / appendix-
let section-num = 1_DIGIT "." appendix-let = 1*CAP "." CAP = %x41-5A
; A-Z DIGIT = %x30-39 ; 0-9
6. Security Considerations
Since RFCs are sometimes exchanged outside the normal Web sandboxing
mechanism (e.g. rsync to a mirror) then loaded from a local file,
more care must be taken with the HTML than is ordinary on the Web. In
particular, the intent with the format is to forbid any embedded code
such as JavaScript as well as all mechanisms that could be used to
execute code outside of the browser such as plugins or non-static
media (such as video).
7. IANA Considerations
TBD
8. Appendix A. Allowable Subset of HTML
This section collects all of the elements that are allowed in the
HTML RFC format. Each element is listed with a set of allowed
attributes, and a list of the parent elements in which the element
may be placed. The attributes class, id, and lang are allowed on all
elements. All other elements, attributes, and nesting approaches
MUST NOT be used.
+------------+----------------------------------------+-------------+
| Element | Attributes | Parents |
+------------+----------------------------------------+-------------+
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| a | href, title | address, |
| | | div, |
| | | figcaption, |
| | | h2, h3, h4, |
| | | h5, li, p, |
| | | span, td |
| | | |
| address | | div |
| | | |
| blockquote | | figure |
| | | |
| | | html |
| | | |
| br | | td, th |
| | | |
| code | | blockquote, |
| | | li, p, td |
| | | |
| div | | address, , |
| | | div, li |
| | | |
| em | | p, span |
| | | |
| figcaption | | figure |
| | | |
| figure | | div |
| | | |
| h1 | | |
| | | |
| h2 | | div |
| | | |
| h3 | | div |
| | | |
| h4 | | div |
| | | |
| h5 | | div |
| | | |
| head | | html |
| | | |
| html | | |
| | | |
| img | alt;, height, src, width | figure |
| | | |
| li | 1, 1.0, 1.1, 10, 10646-1, 16, 2, 2026, | ol, ul |
| | 2026., 206, 2119., 2418., 2739., 3.2, | |
| | 329, 3978, 4, 4748, 495, 617, 79, a, | |
| | abbrev, abnf, abnf., about, | |
| | additional, all, alpha, also, alt;o, | |
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| | among, an, analyzer, and, any, | |
| | applications, are, as, at, audio, | |
| | augmented, authors, available, backus- | |
| | naur, balances, bcp, be, been, | |
| | beginning, benefit, best, between, | |
| | bnf, both, box, but, by, called, can, | |
| | capitalized., cases, channel., | |
| | character, characteristic, checking, | |
| | chromaticity, color, common, | |
| | communities, community, compactness, | |
| | compatibility, compatible, concerning, | |
| | constraints, contributions, | |
| | contributors, core, coyote, creation, | |
| | current, data, data-xml, day, define, | |
| | defines, definitions, delivery, | |
| | depths, described, describes, | |
| | designed, desirable, details, | |
| | detection, developed, development, | |
| | differences, discussion, display, | |
| | document, document:, documents, | |
| | documents., email, encoding, | |
| | encodings, encompasses, ensure, | |
| | entities, errors., exchanging, | |
| | extensible, extensions, file, follow, | |
| | for, force, form, formal, format, | |
| | formatted, from, full, fullname, | |
| | fully, gamma, gif, graphics, groups, | |
| | guidelines, has, have, heterogeneous, | |
| | hill, holders., how, identifying, iec, | |
| | ietf, ietf., image, images, images., | |
| | improved, in, including, incorporate, | |
| | indicate, individuals, information, | |
| | initials, integrity, intellectual, | |
| | intended, interchange., internet, | |
| | interpreted, involve, ipr, is, iso, | |
| | it, key, language, large, led, | |
| | legitimate, level, lexical, made, | |
| | many, markup, mass., matching, may, | |
| | media, meet., memo, memo., modified, | |
| | month, most, much, mult;iple, must, | |
| | name, naming, near, need, network, | |
| | not, note, object, object., | |
| | objectives, obsoletes, octets, of, | |
| | often, on, online, option., optional, | |
| | originally, other, over, palo, | |
| | paragraph, parsers, participants, | |
| | patent, patent-free, permitting, | |
| | phrase, plus, png, policies, popular, | |
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| | possible., power., practices, | |
| | preserving, private, progressive, | |
| | property, proposal, proposed, provide, | |
| | provides, providing, public, range, | |
| | ranges., raster, reasonable, | |
| | recommended, reference, register, | |
| | related, relative, rely, replace, | |
| | replacement, replaces, | |
| | representational, representing, | |
| | requests, required, requirement, | |
| | requirements, research, respecting, | |
| | retain, revision, rfc, rfc2083, | |
| | rfc2119, rfc2397, rfc3629, rfc3979, | |
| | rfc5234, rfc5378, rfc5646, rfc6350, | |
| | rfcs, rights, rule, s, sample, | |
| | section, semantics, set, several, | |
| | shall, sheets, should, signify, | |
| | simple, simplicity, so, software, | |
| | specification, specification., | |
| | specifications, specifications., | |
| | specifications:, specifies, standard, | |
| | standards, storage, store, streamable, | |
| | structured, style, such, suggestions, | |
| | supplies, surname, syntax, syntax., | |
| | systems., tags, target, technical, | |
| | technologies, technology, telephone, | |
| | that, the, their, these, they, this, | |
| | tiff., to, track, transformation, | |
| | transmission, transparent, truecolor, | |
| | type, universal, updates, url, us- | |
| | ascii, use, used, used., user-defined, | |
| | uses, utf-8, value, values, variety, | |
| | vcard, vector, version, viewing, well, | |
| | well-compressed, were, where, which, | |
| | while, who, wide, with, within, words, | |
| | work, worked, working, world, writing, | |
| | year | |
| | | |
| meta | charset, content, name | head |
| | | |
| ol | | div |
| | | |
| p | | div, li, td |
| | | |
| pre | | div, figure |
| | | |
| span | | address, |
| | | div, li, p, |
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| | | span |
| | | |
| strong | | p, pre |
| | | |
| svg | height, viewbox, width | figure |
| | | |
| table | | div, figure |
| | | |
| t | | table |
| | | |
| td | colspan | tr |
| | | |
| th | colspan | tr |
| | | |
| thead | | table |
| | | |
| title | | head |
| | | |
| tr | | t, thead |
| | | |
| ul | | div, li, |
| | | td, ul |
+------------+----------------------------------------+-------------+
9. Appendix B. CSS Classes with Special Meaning
Although the author can add class information to any element, the
following class names have special meaning in an HTML RFC:
+------------------+---------+
| Class | Meaning |
+------------------+---------+
| adr | |
| | |
| appendix | |
| | |
| ascii | |
| | |
| author | |
| | |
| authors | |
| | |
| code | |
| | |
| company | |
| | |
| country-name | |
| | |
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| date | |
| | |
| docName | |
| | |
| edge | |
| | |
| email | |
| | |
| expires | |
| | |
| family-name | |
| | |
| figref | |
| | |
| fn | |
| | |
| given-name | |
| | |
| graph | |
| | |
| hidden | |
| | |
| identifiers | |
| | |
| initial | |
| | |
| initials | |
| | |
| invalid | |
| | |
| languag-hmtl | |
| | |
| language-abnf | |
| | |
| language-c | |
| | |
| language-html | |
| | |
| locality | |
| | |
| n | |
| | |
| nickname | |
| | |
| node | |
| | |
| note | |
| | |
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| org | |
| | |
| pdu | |
| | |
| postal-code | |
| | |
| published | |
| | |
| ref | |
| | |
| reflinks | |
| | |
| region | |
| | |
| rfc2119 | |
| | |
| rfceditor-remove | |
| | |
| section | |
| | |
| sectref | |
| | |
| self-ref | |
| | |
| sequence | |
| | |
| series | |
| | |
| series-info | |
| | |
| status | |
| | |
| street-address | |
| | |
| surname | |
| | |
| title | |
| | |
| toc | |
| | |
| todo | |
| | |
| trust200902 | |
| | |
| vcard | |
| | |
| version | |
| | |
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| workgroup | |
+------------------+---------+
10. Appendix C. Element IDs with Special Meaning
Although the author can add an id attribute to any element, the
following id values SHOULD NOT be used except for the role defined
for each below:
ID Meaning document Data about the document, including dates, name,
version, etc.
title The title of the document, usually applied to a <h1> element.
abstract The abstract for the document, usually applied to a <div>
element that contains a heading and paragraphs of text. ipr
The Intellectual Property Rights associated with the document. The
class attribute of the same element will contain a machine-readable
IPR statement name from this list:
o trust200902: This is appropriate for most drafts, where the entire
content of the draft is written by the draft's authors, or all
authors of other material have given explicit permission to use
their work.
o noModificationTrust200902: This is appropriate for drafts where
the authors wish to place the additional condition that if the
draft is published as an RFC, it must have no changes other than
formatting. An example might be a document published by another
organization that permits copying but not modification.
o noDerivativesTrust200902: This is appropriate for drafts not
intended to be published as RFCs.
o pre5378Trust200902: This is appropriate for drafts that include
material submitted to the IETF prior to RFC 5378 (10 Nov 2008),
where the authors of that material have not given explicit
permission to use their work in this draft. An example might be a
draft using material from an RFC whose author has died or cannot
be located, or who thinks your draft is stupid.
The element with this id will contain all of the IPR and status
boilerplate text
Note: an IANA registry may be required for this attribute in the
future.
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venue The venue for discussion. Inside the element tagged with this
id will be one or more <a> elements that describe the discussion
venue for Internet-Drafts.
toc The Table of Contents
references The section containing bibliographical data, including
sections for normative and informative references.
normative The section containing normative document references.
informative The section containing informative document references.
authors The section containing data about the authors of the
document.
security The section containing the Security Considerations for the
document.
iana The section containing the IANA Considerations for the document.
acknowledgments The section containing the author's acknowledgments.
11. Acknowledgments
The author gratefully acknowledges the contributions of: Patrick
Linskey
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[W3C.CR-html5-20130806]
Berjon, R., Faulkner, S., Leithead, T., Navara, E.,
O'Connor, E., and S. Pfeiffer, "HTML5", World Wide
Web Consortium CR CR-html5-20130806, August 2013,
<http://www.w3.org/TR/2013/CR-html5-20130806>.
[W3C.REC-CSS2-20110607]
Bos, B., A‡elik, 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>.
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12.2. Informative References
[I-D.brownlee-svg-rfc]
Brownlee, N., "SVG Drawings for RFCs: SVG 1.2 RFC", draft-
brownlee-svg-rfc-04 (work in progress), April 2014.
[I-D.iab-styleguide]
Flanagan, H., "RFC Style Guide", draft-iab-styleguide-02
(work in progress), April 2014.
[I-D.hoffman-xml2rfc]
Hoffman, P., "The 'XML2RFC' version 3 Vocabulary", draft-
hoffman-xml2rfc-08 (work in progress), May 2014.
Authors' Addresses
Joe Hildebrand
Cisco Systems, Inc.
Email: jhildebr@cisco.com
Heather Flanagan
RFC Editor
Email: rse@rfc-editor.org
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