Internet DRAFT - draft-ietf-justfont-toplevel
draft-ietf-justfont-toplevel
Network Working Group C. Lilley
Internet-Draft W3C
Intended status: Standards Track December 13, 2016
Expires: June 16, 2017
The font Top Level Type
draft-ietf-justfont-toplevel-06
Abstract
This memo serves to register and document the "font" Top Level Type,
under which the Internet Media subtypes for representation formats
for fonts may be registered. This document also serves as a
registration application for a set of intended subtypes, which are
representative of some existing subtypes already in use, and
currently registered under the "application" tree by their separate
registrations.
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 June 16, 2017.
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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Specification Development
[Note to the RFC Editor: Please remove this section upon
publication.]
This section is non-normative. The source for this specification is
maintained on GitHub [1]. The issues list [2] is also on GitHub.
Discussion should be on the mailing list justfont@ietf.org [3].
2. Introduction
The process of setting type in computer systems and other forms of
text presentation systems uses fonts in order to provide visual
representations of the glyphs. Just as with images, for example,
there are a number of ways to represent the visual information of the
glyphs. Early font formats often used bitmaps, as these could have
been carefully tuned for maximum readability at a given size on low-
resolution displays. More recently, scalable vector outline fonts
have come into widespread use: in these fonts, the outlines of the
glyphs are described, and the presentation system renders the outline
in the desired position and size.
Over time, a number of standard formats for recording font
descriptions have evolved. This document defines a new top-level
Internet Media Type "font" according to Section 4.2.7 of [RFC6838].
This top-level type indicates that the content specifies font data.
Under this top-level type, different representation formats of fonts
may be registered.
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 RFC 2119 [RFC2119].
3. Background and Justification
Historically there has not been a registration of formats for fonts.
More recently, there have been several representation formats
registered as media subtypes under the "application" top-level type
(for example, application/font-woff). However, with the rapid
adoption of web fonts (based on the data from HTTP Archive
[HTTP-Archive-Trends] showing a huge increase in web font usage from
1% in the end of 2010 to 50% across all sites in the beginning of
2015) custom fonts on the web have become a core web resource. As
the in-depth analysis [Font-Media-Type-Analysis] shows, the lack of
the intuitive top-level font type is causing significant confusion
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among developers - while currently defined font subtypes are severely
under-utilized there are many more sites that already use non-
existent (but highly intuitive) media types such as "font/woff",
"font/ttf" and "font/truetype". At the same time, the majority of
sites resort to using generic types such as "application/octet-
stream", "text/plain" and "text/html"; or use unregistrable types
such as "application/x-font-ttf".
Contrary to the expectations of the W3C WebFonts Working Group which
developed WOFF, the officially defined media types such as
"application/font-woff" and "application/font-sfnt" see a very
limited use - their adoption rates trail far behind as the actual use
of web fonts continues to increase. The members of the W3C WebFonts
WG concluded that the use of "application" top-level type is not
ideal. First, the "application" sub-tree is treated (correctly) with
great caution with respect to viruses and other active code.
Secondly, the lack of a top-level type means that there is no
opportunity to have a common set of optional parameters, such as are
specified here. Third, fonts have a unique set of licensing and
usage restrictions, which makes it worthwhile to identify this
general category with a unique top-level type.
The W3C WebFonts WG decided [WG-tlt] that the situation can be
significantly improved if a set of font media types is registered
using "font" as a dedicated top-level type. Based on the data
analysis presented above, we conclude that it is the presence of
simple and highly intuitive media types for images that caused their
widespread adoption, where the correct usage of existing media types
reaches over 97% for all subtypes in the "image" tree. The WG
considers that, considering a rapid adoption of fonts on the web, the
registration of the top-level media type for fonts along with the
intuitive set of subtypes that reflect popular and widely used data
formats would further stimulate the adoption of web fonts,
significantly simplify web server configuration process and
facilitate the proper use of media types for fonts.
4. Security Considerations
Fonts are interpreted data structures that represent collections of
different tables containing data that represent different types of
information, including glyph outlines in various formats, hinting
instructions, metrics and layout information for multiple languages
and writing systems, rules for glyph substitution and positioning,
etc. In particular, the hinting instructions for TrueType glyphs
represent executable code which has the potential to be maliciously
constructed (for example, intended to hang the interpreter). There
are many existing, already standardized font table tags and formats
that allow an unspecified number of entries containing predefined
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data fields for storage of variable length binary data. Many
existing font formats (TrueType [truetype-wiki], OpenType and OFF
[opentype-wiki], SIL Graphite, WOFF, etc.) are based on the table-
based SFNT (scalable font) format which is extremely flexible, highly
extensible and offers an opportunity to introduce additional table
structures when needed, in an upward-compatible way that would not
affect existing font rendering engines and text layout
implementations. However, this very extensibility may present
specific security concerns - the flexibility and ease of adding new
data structures makes it easy for any arbitrary data to be hidden
inside a font file. There is a significant risk that the flexibility
of font data structures may be exploited to hide malicious binary
content disguised as a font data component.
Fonts may contain 'hints', which are programmatic instructions that
are executed by the font engine for the alignment of graphical
elements of glyph outlines with the target display pixel grid.
Depending on the font technology utilized in the creation of a font
these hints may represent active code interpreted and executed by the
font rasterizer. Even though hints operate within the confines of
the glyph outline conversion system and have no access outside the
font rendering engine, hint instructions can be, however, quite
complex, and a maliciously designed complex font could cause undue
resource consumption (e.g. memory or CPU cycles) on a machine
interpreting it. Indeed, fonts are sufficiently complex that most
(if not all) interpreters cannot be completely protected from
malicious fonts without undue performance penalties.
Widespread use of fonts as necessary components of visual content
presentation warrants that careful attention should be given to
security considerations whenever a font is either embedded into an
electronic document or transmitted alongside media content as a
linked resource. While many existing font formats provide certain
levels of protection of data integrity (such mechanisms include e.g.
checksums and digital signatures), font data formats provide neither
privacy nor confidentiality protection internally; if needed, such
protection should be provided externally.
5. IANA Considerations
This specification registers a new top-level type, "font", in the
standards tree; adds it as an alternative value of "Type Name" in the
media types registration form [Media-Type-Registration]; and
registers several subtypes for it.
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5.1. Definition and Encoding
The "font" as the primary media content type indicates that the
content identified by it requires certain graphic subsystem such as
font rendering engine (and, in some cases, text layout and shaping
engine) to process it as font data, which in turn may require certain
level of hardware capabilities such as certain levels of CPU
performance and available memory. The "font" media type does not
provide any specific information about the underlying data format and
how the font information should be interpreted - the subtypes defined
within a "font" tree name the specific font formats. Unrecognized
sub-types of "font" should be treated as "application/octet-stream".
Implementations may pass unrecognized subtypes to a common font-
handling system, if such a system is available.
5.2. Fragment Identifiers for Font Collections
Fragment identifiers for font collections identify one font in the
collection by the PostScript name (name ID=6) [ISO.14496-22.2015].
This is a string, no longer than 63 characters and restricted to the
printable ASCII subset, codes 33 - 126, except for the 10 characters
'[', ']', '(', ')', '{', '}', '<', '>', '/', '%' which are forbidden
by [ISO.14496-22.2015].
In addition, the following 6 characters could occur in the PostScript
name but are forbidden in fragments by [RFC3986] and thus must be
escaped: '"', '#', '\', '^', '`', '|'.
If (following un-escaping) this string matches one of the PostScript
names in the name table, that font is selected. For example, "#Foo-
Bold" refers to the font with PostScript name "Foo-Bold" and
"#Caret%5Estick" refers to the font with PostScript name
"Caret^stick". If the name does not match, or if a fragment is not
specified, the first font in the collection is matched. Note that
the order of fonts in collections may change as the font is revised,
so relying on a particular font in a collection always being first is
unwise.
5.3. Registration Procedure
New font formats should be registered using the online form
[Media-Type-Registration]. RFC 6838 [RFC6838] should be consulted on
registration procedures. In particular the font specification should
preferably be freely available. If the font format can contain
multiple fonts, a fragment identifier syntax should also be defined.
Note that new parameter sub-values may be defined in the future. If
an implementation does not recognize a sub-value in the comma-
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separated list, it should ignore the sub-value and continue
processing the other sub-values in the list.
5.4. Subtype Registrations
In this section the initial entries under the top-level 'font' media
type are specified. They also serve as examples for future
registrations.
For each subtype, an @font-face format identifer is listed. This is
for use with the @font-face src descriptor, defined by the CSS3 Fonts
specification [W3C.CR-css-fonts-3-20131003]. That specification is
normative; the identifiers here are informative.
5.4.1. Generic SFNT Font Type
Type name: font
Subtype name: sfnt
Required parameters: None.
Optional parameters:
1) Name: outlines Values: a comma-separated subset of: TTF, CFF,
SVG
This parameter can be used to specify the type of outlines
provided by the font. Value "TTF" shall be used when a font
resource contains glyph outlines in TrueType format, value
"CFF" shall be used to identify fonts containing PostScript/CFF
outlines [cff-wiki], and value SVG [svg-wiki]shall be used to
identify fonts that include SVG outlines. TTF, CFF or SVG
outlines can be present in various combinations in the same
font file, therefore, this optional parameter is a list
containing one or more items, separated by commas. Order in
the list is not significant.
2) Name: layout
Values: a comma-separated subset of: OTL, AAT, SIL
This parameter identifies the type of implemented support for
advanced text layout features. The predefined values "OTL",
"AAT" and "SIL" respectively indicate support for OpenType text
layout, Apple Advanced Typography or Graphite SIL. More than
one shaping and layout mechanism may be provided by the same
font file, therefore, this optional parameter is a list
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containing one or more items, separated by commas. Order in
the list is not significant.
Encoding considerations: Binary.
Interoperability considerations: As it was noted in the first
paragraph of the "Security considerations" section, a single font
file can contain encoding of the same glyphs using several
different representations, e.g., both TrueType and PostScript
(CFF) outlines. Existing font rendering engines may not be able
to process some of the particular outline formats, and downloading
a font resource that contains only unsupported glyph data format
would be futile. Therefore, it is useful to clearly identify the
format of the glyph outline data within a font using an optional
parameter, and allow applications to make decisions about
downloading a particular font resource sooner. Similarly, another
optional parameter identifies the type of text shaping and layout
mechanism that is provided by a font.
Published specification: ISO/IEC 14496-22 "Open Font Format" (OFF)
specification [ISO.14496-22.2015] being developed by ISO/IEC SC29/
WG11.
Applications that use this media type: All applications that are
able to create, edit or display textual media content.
Note that font/sfnt is an abstract type, from which the (widely
used in practice) font/ttf and font/otf types are conceptually
derived. Use of font/sfnt is likely to be rare in practice, and
might be confined to
uncommon combinations such as font/sfnt; outlines=sil which do
not have a shorter type
cases where a new parameter value is registered
test cases, experimentation, etc
Additional information:
Magic number(s): The TrueType fonts and OFF / OpenType fonts
containing TrueType outlines should use 0x00010000 as the
'sfnt' version number.
The OFF / OpenType fonts containing CFF data should use the tag
'OTTO' as 'sfnt' version number.
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File extension(s): Font file extensions used for OFF / OpenType
fonts: .ttf, .otf
Typically, .ttf extension is only used for fonts containing
TrueType outlines, while .otf extension can be used for any
OpenType/OFF font, either with TrueType or CFF outlines.
Macintosh file type code(s): (no code specified)
Macintosh Universal Type Identifier code: "public.font"
@font-face Format: none.
Fragment Identifiers none.
Deprecated Alias: The existing registration "application/font-
sfnt" is deprecated in favor of "font/sfnt".
Person & email address to contact for further information: Vladimir
Levantovsky (vladimir.levantovsky@monotype.com).
Intended usage: COMMON
Restrictions on usage: None
Author: The ISO/IEC 14496-22 "Open Font Format" specification is a
product of the ISO/IEC JTC1 SC29/WG11.
Change controller: The ISO/IEC has change control over this
specification.
5.4.2. TTF Font Type
Type name: font
Subtype name: ttf
Required parameters: None.
Optional parameters:
Name: layout Values: a comma-separated subset of: OTL, AAT, SIL
This parameter identifies the type of support mechanism for
advanced text layout features. The predefined values "OTL",
"AAT" and "SIL" respectively indicate support for OpenType text
layout, Apple Advanced Typography or Graphite SIL. More than
one shaping and layout mechanism may be provided by the same
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font file, therefore, this optional parameter is a list
containing one or more items, separated by commas. Order in
the list is not significant.
Encoding considerations: Binary.
Interoperability considerations: As it was noted in the first
paragraph of the "Security considerations" section, a single font
file can contain encoding of the same glyphs using several
different representations, e.g., both TrueType and PostScript
(CFF) outlines. Existing font rendering engines may not be able
to process some of the particular outline formats, and downloading
a font resource that contains only unsupported glyph data format
would be futile. Therefore, it is useful to clearly identify the
format of the glyph outline data within a font using an optional
parameter, and allow applications to make decisions about
downloading a particular font resource sooner. Similarly, another
optional parameter identifies the type of text shaping and layout
mechanism that is provided by a font.
Published specification: ISO/IEC 14496-22 "Open Font Format" (OFF)
specification [ISO.14496-22.2015] being developed by ISO/IEC SC29/
WG11.
Applications that use this media type: All applications that are
able to create, edit or display textual media content.
Additional information:
Magic number(s): The TrueType fonts and OFF / OpenType fonts
containing TrueType outlines should use 0x00010000 as the
'sfnt' version number.
File extension(s): Font file extensions used for TrueType / OFF /
OpenType fonts: .ttf, .otf
Typically, .ttf extension is only used for fonts containing
TrueType outlines, while .otf extension may be used for any
OpenType/OFF font, either with TrueType or CFF outlines.
Macintosh file type code(s): (no code specified)
Macintosh Universal Type Identifier code: "public.truetype-font"
@font-face Format: truetype
Fragment Identifiers none.
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Person & email address to contact for further information: Vladimir
Levantovsky (vladimir.levantovsky@monotype.com).
Intended usage: COMMON
Restrictions on usage: None
Author: The ISO/IEC 14496-22 "Open Font Format" specification is a
product of the ISO/IEC JTC1 SC29/WG11.
Change controller: The ISO/IEC has change control over this
specification.
5.4.3. OTF Font Type
Type name: font
Subtype name: otf
Required parameters: None.
Optional parameters
Name: outlines Values: a comma-separated subset of: TTF, CFF, SVG
This parameter can be used to specify the type of outlines
provided by the font. Value "TTF" shall be used when a font
resource contains glyph outlines in TrueType format, value
"CFF" shall be used to identify fonts containing PostScript/CFF
outlines, and value SVG shall be used to identify fonts that
include SVG outlines. TTF, CFF or SVG outlines can be present
in various combinations in the same font file, therefore, this
optional parameter is a list containing one or more items,
separated by commas. Order in the list is not significant.
Encoding considerations: Binary.
Interoperability considerations: As it was noted in the first
paragraph of the "Security considerations" section, a single font
file can contain encoding of the same glyphs using several
different representations, e.g., both TrueType and PostScript
(CFF) outlines. Existing font rendering engines may not be able
to process some of the particular outline formats, and downloading
a font resource that contains only unsupported glyph data format
would be futile. Therefore, it is useful to clearly identify the
format of the glyph outline data within a font using an optional
parameter, and allow applications to make decisions about
downloading a particular font resource sooner. Similarly, another
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optional parameter identifies the type of text shaping and layout
mechanism that is provided by a font.
Published specification: ISO/IEC 14496-22 "Open Font Format" (OFF)
specification [ISO.14496-22.2015] being developed by ISO/IEC SC29/
WG11.
Applications that use this media type: All applications that are
able to create, edit or display textual media content.
Additional information:
Magic number(s): The TrueType fonts and OFF / OpenType fonts
containing TrueType outlines should use 0x00010000 as the
'sfnt' version number.
The OFF / OpenType fonts containing CFF outlines should use the
tag 'OTTO' as 'sfnt' version number. There is no magic number
for SVG outlines; these are always accompanied by either
TrueType or CFF outlines and thus use the corresponding magic
number.
File extension(s): Font file extensions used for OFF / OpenType
fonts: .ttf, .otf
Typically, .ttf extension is only used for fonts containing
TrueType outlines, while .otf extension can be used for any
OpenType/OFF font, either with TrueType, CFF or SVG outlines.
Macintosh file type code(s): (no code specified)
Macintosh Universal Type Identifier code: "public.opentype-font"
@font-face Format: opentype
Fragment Identifiers none.
Person & email address to contact for further information: Vladimir
Levantovsky (vladimir.levantovsky@monotype.com).
Intended usage: COMMON
Restrictions on usage: None
Author: The ISO/IEC 14496-22 "Open Font Format" specification is a
product of the ISO/IEC JTC1 SC29/WG11.
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Change controller: The ISO/IEC has change control over this
specification.
5.4.4. Collection Font Type
Type name: font
Subtype name: collection
Required parameters: None.
Optional parameters
Name: outlines Values: a comma-separated subset of: TTF, CFF, SVG
This parameter can be used to specify the type of outlines
provided by the font. Value "TTF" shall be used when a font
resource contains glyph outlines in TrueType format, value
"CFF" shall be used to identify fonts containing PostScript/CFF
outlines, and value SVG shall be used to identify fonts that
include SVG outlines. TTF, CFF or SVG outlines can be present
in various combinations in the same font file, therefore, this
optional parameter is a list containing one or more items,
separated by commas. Order in the list is not significant.
Encoding considerations: Binary.
Interoperability considerations: As it was noted in the first
paragraph of the "Security considerations" section, a single font
file can contain encoding of the same glyphs using several
different representations, e.g., both TrueType and PostScript
(CFF) outlines. Existing font rendering engines may not be able
to process some of the particular outline formats, and downloading
a font resource that contains only unsupported glyph data format
would be futile. Therefore, it is useful to clearly identify the
format of the glyph outline data within a font using an optional
parameter, and allow applications to make decisions about
downloading a particular font resource sooner. Similarly, another
optional parameter identifies the type of text shaping and layout
mechanism that is provided by a font.
Published specification: ISO/IEC 14496-22 "Open Font Format" (OFF)
specification [ISO.14496-22.2015] being developed by ISO/IEC SC29/
WG11.
Applications that use this media type: All applications that are
able to create, edit or display textual media content.
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Additional information:
Magic number(s): The TrueType fonts and OFF / OpenType fonts
containing TrueType outlines should use 0x00010000 as the
'sfnt' version number.
The OFF / OpenType fonts containing CFF outlines should use the
tag 'OTTO' as 'sfnt' version number. There is no magic number
for SVG outlines; these are always accompanied by either
TrueType or CFF outlines and thus use the corresponding magic
number.
File extension(s): Font file extensions used for OFF / TrueType
and OpenType fonts: .ttc
Macintosh file type code(s): (no code specified)
Macintosh Universal Type Identifier code: "public.truetype-
collection-font"
@font-face Format: collection
Fragment Identifiers: See Section 5.2.
Person & email address to contact for further information: Vladimir
Levantovsky (vladimir.levantovsky@monotype.com).
Intended usage: COMMON
Restrictions on usage: None
Author: The ISO/IEC 14496-22 "Open Font Format" specification is a
product of the ISO/IEC JTC1 SC29/WG11.
Change controller: The ISO/IEC has change control over this
specification.
5.4.5. WOFF 1.0
Type name: font
Subtype name: woff
Required parameters: None.
Optional parameters: None.
Encoding considerations: Binary.
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Interoperability considerations: None.
Published specification: This media type registration updates the
WOFF specification [W3C.REC-WOFF-20121213] at W3C.
Applications that use this media type: WOFF is used by Web browsers,
often in conjunction with HTML and CSS.
Additional information:
Magic number(s): The signature field in the WOFF header MUST
contain the "magic number" 0x774F4646 ('wOFF')
File extension(s): woff
Macintosh file type code(s): (no code specified)
Macintosh Universal Type Identifier code: "org.w3.woff"
@font-face Format: woff
Fragment Identifiers: none.
Deprecated Alias: The existing registration "application/font-
woff" is deprecated in favor of "font/woff".
Person & email address to contact for further information: Chris
Lilley (www-font@w3.org).
Intended usage: COMMON
Restrictions on usage: None
Author: The WOFF specification is a work product of the World Wide
Web Consortium's WebFonts Working Group.
Change controller: The W3C has change control over this
specification.
5.4.6. WOFF 2.0
Type name: font
Subtype name: woff2
Required parameters: None.
Optional parameters: None.
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Encoding considerations: Binary.
Interoperability considerations: WOFF 2.0 is an improvement on WOFF
1.0. The two formats have different Internet Media Types,
different @font-face formats, and may be used in parallel.
Published specification: This media type registration is extracted
from the WOFF 2.0 specification [W3C.CR-WOFF2-20150414] at W3C.
Applications that use this media type: WOFF 2.0 is used by Web
browsers, often in conjunction with HTML and CSS.
Additional information:
Magic number(s): The signature field in the WOFF header MUST
contain the "magic number" 0x774F4632 ('wOF2')
File extension(s): woff2
Macintosh file type code(s): (no code specified)
Macintosh Universal Type Identifier code: "org.w3.woff2"
@font-face Format: woff2
Fragment Identifiers: See Section 5.2.
Person & email address to contact for further information: Chris
Lilley (www-font@w3.org).
Intended usage: COMMON
Restrictions on usage: None
Author: The WOFF2 specification is a work product of the World Wide
Web Consortium's WebFonts Working Group.
Change controller: The W3C has change control over this
specification.
6. References
6.1. Normative References
[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>.
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[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>.
[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>.
[W3C.CR-css-fonts-3-20131003]
Daggett, J., "CSS Fonts Module Level 3", World Wide Web
Consortium CR CR-css-fonts-3-20131003, October 2013,
<http://www.w3.org/TR/2013/CR-css-fonts-3-20131003>.
[ISO.14496-22.2015]
International Organization for Standardization, "Coding of
audio-visual objects Part 22: Open Font Format",
ISO Standard 14496-22, 10 2015,
<http://standards.iso.org/ittf/PubliclyAvailableStandards/
c066391_ISO_IEC_14496-22_2015.zip>.
[W3C.REC-WOFF-20121213]
Kew, J., Leming, T., and E. Blokland, "WOFF File Format
1.0", World Wide Web Consortium Recommendation REC-WOFF-
20121213, December 2012,
<http://www.w3.org/TR/2012/REC-WOFF-20121213>.
[W3C.CR-WOFF2-20150414]
Levantovsky, V. and R. Levien, "WOFF File Format 2.0",
World Wide Web Consortium WD CR-WOFF2-20150414, March
2016, <https://www.w3.org/TR/2016/CR-WOFF2-20160315/>.
6.2. Informative References
[cff-wiki]
"CFF", <https://en.wikipedia.org/wiki/
PostScript_fonts#Compact_Font_Format>.
[opentype-wiki]
"OpenType", <https://en.wikipedia.org/wiki/OpenType>.
[truetype-wiki]
"TrueType", <https://en.wikipedia.org/wiki/TrueType>.
[svg-wiki]
"SVG", <https://en.wikipedia.org/wiki/
Scalable_Vector_Graphics>.
Lilley Expires June 16, 2017 [Page 16]
Internet-Draft The font Top Level Type December 2016
[HTTP-Archive-Trends]
Kuetell, D., "HTTP Archive trend analysis", March 2015,
<http://httparchive.org/trends.php?s=All&minlabel=Nov+15+2
010&maxlabel=Feb+15+2015#perFonts>.
[Font-Media-Type-Analysis]
Kuetell, D., "Web Font Media Type (mime type) Analysis
2015", 2015, <http://goo.gl/zbDhUN>.
[WG-tlt] W3C, "ACTION-164: Bring widely used top-level-type to w3c-
ietf liaison", 2015, <https://www.w3.org/Fonts/WG/track/
actions/164>.
[Media-Type-Registration]
IANA, "Application for a Media Type",
<http://www.iana.org/form/media-types>.
6.3. URIs
[1] https://github.com/svgeesus/ietf-justfont
[2] https://github.com/svgeesus/ietf-justfont/issues
[3] mailto:justfont@ietf.org
Author's Address
Chris Lilley
W3C
2004 Route des Lucioles
Sophia Antipolis 06902
France
Email: chris@w3.org
Lilley Expires June 16, 2017 [Page 17]
