| Rfc | 7763 |
|---|
| Title | The text/markdown Media Type |
|---|
| Author | S. Leonard |
|---|
| Date | March 2016 |
|---|
| Format: | TXT,
HTML |
|---|
| Status: | INFORMATIONAL |
|---|
|
Internet Engineering Task Force (IETF) S. Leonard
Request for Comments: 7763 Penango, Inc.
Category: Informational March 2016
ISSN: 2070-1721
The text/markdown Media Type
Abstract
This document registers the text/markdown media type for use with
Markdown, a family of plain-text formatting syntaxes that optionally
can be converted to formal markup languages such as HTML.
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 Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7763.
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
(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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. This Is Markdown! Or: Markup and Its Discontents . . . . . 2
1.2. Markdown Is About Writing and Editing . . . . . . . . . . . 3
1.3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Markdown Media Type Registration Application . . . . . . . . . 5
3. Fragment Identifiers . . . . . . . . . . . . . . . . . . . . . 8
3.1. Parameters . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Content Disposition and preview-type . . . . . . . . . . . . . 9
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6.1. Markdown Variants . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
1.1. This Is Markdown! Or: Markup and Its Discontents
In computer systems, textual data is stored and processed using a
continuum of techniques. On the one end is plain text: computer-
encoded text that consists only of a sequence of code points from a
given standard, with no other formatting or structural information
[UNICODE]. (On the other end is binary data, which computer systems
store and process with bit-for-bit accuracy.) Many of these standards
include control characters that are used as in-band signaling to
cause effects other than the addition of a symbol (or grapheme) to
the text.
Markup offers an alternative means to encode this signaling
information by overloading certain graphic characters (see, e.g.,
[ISO646]) with additional meanings. Therefore, markup languages
allow for annotating a document in a syntactically distinguishable
way from the text, while keeping the annotations printable. Markup
languages are (reasonably) well-specified and tend to follow (mostly)
standardized syntax rules. Examples of formal markup languages
include Standard Generalized Markup Language (SGML), HTML, XML, and
LaTeX. Standardized rules lead to interoperability between markup
processors, but they impose skill requirements on new users that lead
to markup languages becoming less accessible to beginners. These
rules also reify "validity": content that does not conform to the
rules is treated differently (i.e., is rejected) than content that
conforms.
In contrast to formal markup languages, lightweight markup languages
use simple syntaxes; they are designed to be easy for humans to enter
and understand with basic text editors. Markdown, the subject of
this document, began as an /informal/ plain-text formatting syntax
[MDSYNTAX] and Perl script HTML/XHTML processor [MARKDOWN] targeted
at non-technical users using unspecialized tools, such as plain-text
email clients. [MDSYNTAX] explicitly rejects the notion of validity:
there is no such thing as "invalid" Markdown. If the Markdown
content does not result in the "right" output (defined as output that
the author wants, not output that adheres to some dictated system of
rules), the expectation is that the author should continue
experimenting by changing the content or the processor to achieve the
desired output.
Since its development in 2004 [MARKDOWN], a number of web- and
Internet-facing applications have incorporated Markdown into their
text-entry systems, frequently with custom extensions. Markdown has
thus evolved into a kind of Internet meme [INETMEME] as different
communities encounter it and adapt the syntax for their specific use
cases. Markdown now represents a family of related plain-text
formatting syntaxes and implementations that, while broadly
compatible with humans [HUMANE], are intended to produce different
kinds of outputs that push the boundaries of mutual intelligibility
between software systems.
To support identifying and conveying Markdown, this document defines
a media type and parameters that indicate the Markdown author's
intent on how to interpret the content. This registration draws
particular inspiration from text/troff [RFC4263], which is a plain-
text formatting syntax for typesetting based on tools from the 1960s
("RUNOFF") and 1970s ("nroff", et al.). In that sense, Markdown is a
kind of troff for modern computing. A companion document [RFC7764]
provides additional Markdown background, philosophy, local storage
strategies, and variant registrations (including examples).
1.2. Markdown Is About Writing and Editing
"HTML is a *publishing* format; Markdown is a *writing* format.
Thus, Markdown's formatting syntax only addresses issues that can
be conveyed in plain text." [MDSYNTAX]
The paradigmatic use case for text/markdown is the Markdown editor:
an application that presents Markdown content (which looks like an
email or other piece of plain-text writing) alongside a published
format, so that an author can see results instantaneously and can
tweak his or her input in real time. A significant number of
Markdown editors have adopted "split-screen view" (or "live preview")
technology that looks like Figure 1.
+----------------------------------------------------------------------+
| File Edit (Cloud Stuff) (Fork Me on GitHub) Help |
+----------------------------------------------------------------------+
| [ such-and-such identifier ] [ useful statistics] |
+----------------------------------++----------------------------------+
| (plain text, with || (text/html, likely |
| syntax highlighting) || rendered to screen) |
| || |
|# Introduction ||<h1>Introduction</h1> |
| || |
|## Markdown Is About Writing and /|<h2>Markdown Is About Writing and |
/ Editing ||Editing</h2> |
| || |
|> HTML is a *publishing* format; ||<blockquote><p>HTML is a |
|> Markdown is a *writing* format. || <em>publishing</em> format; |
|> Thus, Markdown's formatting || Markdown is a <em>writing</em> |
|> syntax only addresses issues || format. Thus, Markdown's |
|> that can be conveyed in plain <> formatting syntax only addresses |
|> text. [MDSYNTAX][] || issues that can be conveyed in |
| || plain text. <a href="http://darin/
|The paradigmatic use case for |/gfireball.net/projects/markdown/sy/
|`text/markdown` is the Markdown |/ntax#html" title="Markdown: Syntax/
|editor: an application that |/: HTML">MDSYNTAX</a> |
|presents Markdown content ||</p></blockquote> |
|... || |
| ||<p>The paradigmatic use case for |
|[MDSYNTAX]: http://daringfireball./| <code>text/markdown</code> is the|
/net/projects/markdown/syntax#html || Markdown editor: an application |
|"Markdown: Syntax: HTML" || that presents Markdown content |
| || ...</p> |
+----------------------------------++----------------------------------+
LEGEND: "/" embedded in a vertical line represents a line-continuation
marker, since a line break is not supposed to occur in that content.
Figure 1: Markdown Split-Screen / Live Preview Editor
To get the best results, implementations ought to produce and consume
mutually intelligible and identifiable bits of Markdown. That way,
users on diverse platforms can collaborate with their tools of
choice. Those tools can be desktop-based (MarkdownPad, MultiMarkdown
Composer); browser-based (Dillinger, Markable); integrated widgets
(Discourse, GitHub); general-purpose editors (emacs, vi); or plain
old "Notepad". Additionally, implementations ought to have common
ways to identify particular areas of Markdown content when the
Markdown becomes appreciably large (e.g., book chapters and Internet-
Drafts -- not just blog posts). So that users have the option to use
Markdown in MIME-capable systems to convey their works in progress,
not just their finished products (for which full-blown markups
ranging from text/html to application/pdf are appropriate),
implementations ought to label such Markdown content with a common
media type: text/markdown. This registration facilitates
interoperability between these Markdown editors by conveying the
syntax of the particular Markdown variant and the desired output
format.
1.3. Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Since Markdown signifies a family of related formats with varying
degrees of formal documentation and implementation, this
specification uses the term "variant" to identify such formats.
2. Markdown Media Type Registration Application
This section provides the media type registration application for the
text/markdown media type (see Section 5.6 of [RFC6838]).
Type name: text
Subtype name: markdown
Required parameters:
charset: Per Section 4.2.1 of [RFC6838], charset is REQUIRED.
There is no default value because neither [MDSYNTAX] nor many
popular implementations at the time of this registration do
either. [MDSYNTAX] clearly describes Markdown as a "writing
format"; its syntax rules operate on characters (specifically,
on punctuation) rather than code points. Many Markdown
processors will get along just fine by operating on characters
in the US-ASCII repertoire (specifically punctuation),
blissfully oblivious to other characters or codes.
Optional parameters:
variant: An optional identifier of the specific Markdown variant
that the author intended. The value serves as a "hint" to the
recipient, meaning that the recipient MAY interpret the
Markdown as that variant, but is under no obligation to do so.
When omitted, there is no hint; the interpretation is entirely
up to the receiver and context. This identifier is plain US-
ASCII and case-insensitive. To promote interoperability,
identifiers can be registered in the registry defined in
Section 6. If a receiver does not recognize the variant
identifier, the receiver MAY present the identifier to a user
to inform him or her of it.
Other parameters MAY be included with the media type. The
variant SHOULD define the semantics of such other parameters.
Additionally, the variant MAY be registered under another media
type; this text/markdown registration does not preclude other
registrations.
Encoding considerations:
Markdown content is plain-text content; any octet sequence is
valid as long as it conforms to the character codes of the charset
parameter. See [RFC2046]. Markup characters in [MDSYNTAX] are
limited to printable US-ASCII; however, other variants can define
markup characters outside this range (including control characters
such as NUL and characters encoded in multiple octets).
Security considerations:
Markdown interpreted as plain text is relatively harmless. A text
editor need only display the text. The editor SHOULD take care to
handle control characters appropriately and to limit the effect of
the Markdown to the text-editing area itself; malicious Unicode-
based Markdown could, for example, surreptitiously change the
directionality of the text. An editor for normal text would
already take these control characters into consideration, however.
Markdown interpreted as a precursor to other formats, such as
HTML, carries all of the security considerations as the target
formats. For example, HTML can contain instructions to execute
scripts, redirect the user to other web pages, download remote
content, and upload personally identifiable information. Markdown
also can contain islands of formal markup, such as HTML. These
islands of formal markup may be passed as they are, transformed,
or ignored (perhaps because the islands are conditional or
incompatible) when the Markdown is processed. Since Markdown may
have different interpretations depending on the tool and the
environment, a better approach is to analyze (and sanitize or
block) the output markup, rather than attempting to analyze the
Markdown.
Interoperability considerations:
Markdown variations (some might say "innovations") are designed to
be broadly compatible with humans ("humane"), but not necessarily
with each other. Therefore, syntax in one Markdown derivative may
be ignored or treated differently in another derivative. The
overall effect is a general degradation of the output that
increases with the quantity of variant-specific Markdown used in
the text. When it is desirable to reflect the author's intent in
the output, stick with the variant identified in the variant
parameter, i.e., receivers SHOULD only accept Markdown variants
that they explicitly know about, and senders SHOULD avoid use of
variants that intended recipients are not known to understand.
Published specification: This specification; [MDSYNTAX].
Applications that use this media type:
Markdown conversion tools, Markdown WYSIWYG (What You See is What
You Get) editors, and plain-text editors and viewers; markup
processor targets indirectly use Markdown (e.g., web browsers for
Markdown converted to HTML).
Fragment identifier considerations:
See Section 3.
Additional information:
Magic number(s): None
File extension(s): .md, .markdown
Macintosh file type code(s):
TEXT. A uniform type identifier (UTI) of
"net.daringfireball.markdown", which conforms to
"public.plain-text", is RECOMMENDED [MDUTI]. See [RFC7764] for
other considerations.
Person & email address to contact for further information:
Sean Leonard <dev+ietf@seantek.com>
Restrictions on usage: None.
Author/Change controller: Sean Leonard <dev+ietf@seantek.com>
Intended usage: COMMON
Provisional registration? No
Implementations SHOULD record the value of the variant parameter (and
other parameters if defined by the variant) along with the Markdown
content when the content leaves the domain of formats that are
Internet media type capable. Strategies for doing so are discussed
in [RFC7764].
The Content-Disposition header (particularly the preview-type
parameter) can be used with Markdown content. See Section 4.
3. Fragment Identifiers
[MARKDOWN] does not define any fragment identifiers, but some
variants do, and many types of Markdown processor output (e.g., HTML
or PDF) will have well-defined fragment identifiers. Which fragment
identifiers are available for a given document are variant-defined.
When encoded in a URI, characters that are outside of the fragment
production of [RFC3986] are percent-encoded. The default encoding
(character set) of percent-encoded octets in URIs is the same as the
Markdown content, which is identified by the charset parameter or by
other contextual means. Fragment identifiers SHOULD be considered
case-sensitive, which maintains consistency with HTML. Variants MAY
override the guidance in this paragraph.
At least the first equals sign "=" SHOULD be percent-encoded to
prevent ambiguity as described in the following section.
3.1. Parameters
Similar to application/pdf [RFC3778] and text/plain [RFC5147], this
registration permits a parameter syntax for fragment identifiers.
The syntax is a parameter name, the equals sign "=" (which MUST NOT
be percent-encoded), and a parameter value. To the extent that
multiple parameters can appear in a fragment production, the
parameters SHALL be separated by the ampersand "&" (which MUST NOT be
percent-encoded).
The only parameter defined in this registration is "line", which has
the same meaning as in [RFC5147], i.e., counting is zero-based. For
example: "#line=10" identifies the eleventh line of Markdown input.
Implementers should take heed that different environments and
character sets may have a wide range of code sequences to divide
lines.
Markdown variants are free to define additional parameters.
4. Content Disposition and preview-type
The Content-Disposition header [RFC2183] conveys presentational
information about a MIME entity, using a type and set of parameters.
The parameter preview-type is defined here for Markdown content.
When present, preview-type indicates the Internet media type (and
parameters) of the preview output desired from the processor by the
author. With reference to the "paradigmatic use case" (i.e.,
collaborative Markdown editing) in Section 1.3, the preview-type
parameter primarily affects the "right-hand" side of a Markdown
editor. There is no default value: when absent, a Markdown user
agent can render or display whatever it wants.
The value of this parameter is an Internet media type with optional
parameters. The syntax (including case-sensitivity considerations)
is the same as specified in [RFC2045] for the Content-Type header
(with updates over time, e.g., [RFC2231] and [RFC6532]).
Implementations SHOULD anticipate and support HTML (text/html) and
XHTML (application/xhtml+xml) output, to the extent that a syntax
targets those markup languages. These types ought to be suitable for
the majority of current purposes. However, Markdown is increasingly
becoming integral to workflows where HTML is not the target output;
examples range from TeX, to PDF, to Outline Processor Markup Language
(OPML), and even to entire e-books (e.g., [PANDOC]).
The reflexive media type text/markdown in this parameter value means
that the author does not want to invoke Markdown processing at all:
the receiver SHOULD present the Markdown source as is.
The preview-type parameter can be used for other types of content,
but the precise semantics are not defined here.
5. Example
The following is an example of Markdown as an email attachment:
MIME-Version: 1.0
Content-Type: text/markdown; charset=UTF-8; variant=Original
Content-Disposition: attachment; filename=readme.md;
preview-type="application/xhtml+xml"
Sample HTML 4 Markdown
=============
This is some sample Markdown. [Hooray!][foo]
(Remember that link identifiers are not case-sensitive.)
Bulleted Lists
-------
Here are some bulleted lists...
* One Potato
* Two Potato
* Three Potato
- One Tomato
- Two Tomato
- Three Tomato
More Information
-----------
[.markdown, .md](http://daringfireball.net/projects/markdown/)
has more information.
[fOo]: http://example.com/loc 'Will Not Work with Markdown.pl-1.0.1'
6. IANA Considerations
IANA has registered the media type text/markdown using the
application provided in Section 2 of this document.
IANA has registered preview-type in the "Content Disposition
Parameters" subregistry of the "Content Disposition Values and
Parameters" registry, with the following description: "Internet media
type (and parameters) of the preview output desired from a processor
by the author of the MIME content".
6.1. Markdown Variants
IANA has established a registry called "Markdown Variants". While
the registry has been created in the context of the text/markdown
media type, the registry is intended for broad community use, so
protocols and systems that do not rely on Internet media types can
still tag Markdown content with a common variant identifier. Each
entry in this registry shall consist of basic information about the
variant:
Identifier: unique identifier for the variant
Name: the commonly known name of the variant
Description: a prose description of the variant, including
how it differs from other variants such as
Original
Additional Parameters*: additional Content-Type parameters
Fragment Identifiers*: additional fragment identifier syntaxes and
semantics
References: URIs or other references to documentation
Contact Information: whom to contact (email, URI, phone, address,
etc.)
Expiration Date^: when this provisional registration expires
* (optional)
^ (if provisional)
While the variant parameter is "plain US-ASCII" (see registration
template), the Identifier field (and by implication, all registered
identifiers) SHALL conform to the ABNF [RFC5234]:
ALPHA [*VCHAR (ALPHA / DIGIT)]
For style and compatibility reasons, the Identifier field SHOULD
conform to the ABNF:
ALPHA *( ["-" / "." / "_" / "~"] 1*(ALPHA / DIGIT) )
That is, the identifier MUST start with a letter and MAY contain
punctuation in the middle, but not at the end: the last character
MUST be alphanumeric. The second production uses the same characters
as the "unreserved" rule of [RFC3986] and is designed to be
compatible with characters in other identification systems, e.g.,
filenames. Since the identifier MAY be displayed to a user --
particularly in cases where the receiver does not recognize the
identifier -- the identifier SHOULD be rationally related to the
vernacular name of the variant.
The Name, Description, Additional Parameters, Fragment Identifiers,
References, and Contact Information fields SHALL be in a Unicode
character set (e.g., UTF-8).
The registry includes the registration in Section 6.1.4 (Original
Markdown). [RFC7764] includes additional registrations.
6.1.1. Reserved Identifiers
The registry has the following identifiers RESERVED, as they have
engendered some controversy in the Markdown community. No one is
allowed to register them (or any case variations of them). These
identifiers are not and cannot be registered:
Standard
Common
Markdown
The registry includes the following text in the note field:
The variant names Standard, Common, and Markdown are reserved and
cannot be registered.
6.1.2. Standard of Review
Registrations are made on a First Come, First Served [RFC5226] basis
by anyone with a need to interoperate. While documentation is
required, any level of documentation is sufficient; thus, neither
Specification Required nor Expert Review are warranted. The checks
prescribed by this section can be performed automatically.
All references (including contact information) MUST be verified as
functional at the time of the registration.
As a special "escape valve", registrations can be updated with IETF
Review [RFC5226]. All fields may be updated except the variant
identifier, which is permanent: not even case may be changed.
6.1.3. Provisional Registration
Any registrant may make a provisional registration to reserve a
variant identifier. Only the variant identifier and contact
information fields are required; the rest are optional. Provisional
registrations expire after three months, after which time the variant
identifier may be reused. To make a registration permanent, a
registrant simply needs to complete a permanent registration with the
same identifier as the provisional registration.
6.1.4. Original Markdown
The registry includes this initial variant. A conforming
implementation that processes the variant parameter MUST recognize
this variant (although the processing behavior is not defined here).
Identifier: Original
Name: Markdown
Description:
Gruber's original Markdown syntax.
References:
[MARKDOWN]
[MDSYNTAX]
Contact Information:
(individual) John Gruber <http://daringfireball.net/>
<comments@daringfireball.net>
7. Security Considerations
See the Security considerations entry in Section 2.
8. References
8.1. Normative References
[MARKDOWN] Gruber, J., "Daring Fireball: Markdown", December 2004,
<http://daringfireball.net/projects/markdown/>.
[MDSYNTAX] Gruber, J., "Daring Fireball: Markdown Syntax
Documentation", December 2004,
<http://daringfireball.net/projects/markdown/syntax>.
[MDUTI] Gruber, J., "Daring Fireball: Uniform Type Identifier for
Markdown", August 2011,
<http://daringfireball.net/linked/2011/08/05/
markdown-uti>.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
<http://www.rfc-editor.org/info/rfc2045>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2183] Troost, R., Dorner, S., and K. Moore, Ed., "Communicating
Presentation Information in Internet Messages: The
Content-Disposition Header Field", RFC 2183,
DOI 10.17487/RFC2183, August 1997,
<http://www.rfc-editor.org/info/rfc2183>.
[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded
Word Extensions: Character Sets, Languages, and
Continuations", RFC 2231, DOI 10.17487/RFC2231, November
1997, <http://www.rfc-editor.org/info/rfc2231>.
[RFC3778] Taft, E., Pravetz, J., Zilles, S., and L. Masinter, "The
application/pdf Media Type", RFC 3778,
DOI 10.17487/RFC3778, May 2004,
<http://www.rfc-editor.org/info/rfc3778>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC5147] Wilde, E. and M. Duerst, "URI Fragment Identifiers for the
text/plain Media Type", RFC 5147, DOI 10.17487/RFC5147,
April 2008, <http://www.rfc-editor.org/info/rfc5147>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[RFC6532] Yang, A., Steele, S., and N. Freed, "Internationalized
Email Headers", RFC 6532, DOI 10.17487/RFC6532, February
2012, <http://www.rfc-editor.org/info/rfc6532>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>.
8.2. Informative References
[HUMANE] Atwood, J., "Is HTML a Humane Markup Language?", May 2008,
<http://blog.codinghorror.com/
is-html-a-humane-markup-language/>.
[INETMEME] Solon, O., "Richard Dawkins on the internet's hijacking of
the word 'meme'", June 2013,
<http://www.wired.co.uk/news/archive/2013-06/20/
richard-dawkins-memes>,
<http://www.webcitation.org/6HzDGE9Go>.
[ISO646] International Organization for Standardization,
"Information technology - ISO 7-bit coded character set
for information interchange", ISO Standard 646, 1991.
[PANDOC] MacFarlane, J., "Pandoc", 2014,
<http://johnmacfarlane.net/pandoc/>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<http://www.rfc-editor.org/info/rfc2046>.
[RFC4263] Lilly, B., "Media Subtype Registration for Media Type
text/troff", RFC 4263, DOI 10.17487/RFC4263, January 2006,
<http://www.rfc-editor.org/info/rfc4263>.
[RFC7764] Leonard, S., "Guidance on Markdown: Design Philosophies,
Stability Strategies, and Select Registrations", RFC 7764,
DOI 10.17487/RFC7764, March 2016,
<http://www.rfc-editor.org/info/rfc7764>.
[UNICODE] The Unicode Consortium, "The Unicode Standard, Version
8.0", (Mountain View, CA: The Unicode Consortium, 2015.
ISBN 978-1-936213-10-8),
<http://www.unicode.org/versions/Unicode8.0.0/>.
Author's Address
Sean Leonard
Penango, Inc.
5900 Wilshire Boulevard
21st Floor
Los Angeles, CA 90036
United States
Email: dev+ietf@seantek.com
URI: http://www.penango.com/