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<?xml version="1.0"?>
<!--DOCTYPE rfc SYSTEM "rfc.dtd"-->
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<rfc docName="draft-ietf-justfont-toplevel-current" category="std" ipr='trust200902'>
<front>
<title>The font Top Level Type </title>
<author initials="C" surname="Lilley" fullname="Chris Lilley">
<organization>W3C</organization>
<address>
<postal>
<street>2004 Route des Lucioles</street>
<city>Sophia Antipolis</city>
<code>06902</code>
<country>France</country>
</postal>
<email>chris@w3.org</email>
</address>
</author>
<date day="09" month="December" year="2016"/>
<keyword>Internet Media Types</keyword>
<abstract>
<t>
This memo serves to register and document the <spanx style="verb">font</spanx> 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.
</t>
</abstract>
</front>
<middle>
<section title="Specification Development" anchor="issues">
<t>
[Note to the RFC Editor: Please remove this section upon publication.]
</t>
<t>This section is non-normative. The source for this specification is
<eref target="https://github.com/svgeesus/ietf-justfont">maintained on GitHub</eref>.
The <eref target="https://github.com/svgeesus/ietf-justfont/issues">issues list</eref> is also on GitHub.
Discussion should be on the mailing list <eref target="mailto:justfont@ietf.org">justfont@ietf.org</eref>.
</t>
</section>
<section title="Introduction" anchor="intro">
<t>
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.</t>
<t>
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 <xref target="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.</t>
<t>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 <xref target="RFC2119"/>.</t>
</section>
<section title="Background and Justification">
<t>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 <xref target="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 <xref target="Font-Media-Type-Analysis"/> shows,
the lack of
the intuitive top-level font type is causing significant confusion 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".</t>
<t>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.</t>
<t>The W3C WebFonts WG decided <xref target="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.</t>
</section>
<section title="Security Considerations">
<t>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 data fields for
storage of variable length binary data. Many existing font formats (TrueType
<xref target="truetype-wiki"/>, OpenType
and OFF <xref target="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.</t>
<t>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.</t>
<t>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.</t>
</section>
<section title="IANA Considerations ">
<t>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 <xref target="Media-Type-Registration"/>; and
registers several subtypes for it.
</t>
<section title="Definition and Encoding">
<t>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.</t>
</section>
<section title="Fragment Identifiers for Font Collections" anchor="fragments">
<t>Fragment identifiers for font collections identify one font in the collection by
the PostScript name (name ID=6) <xref target="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
'[', ']', '(', ')', '{', '}', '&lt;', '&gt;', '/', '%' which are forbidden
by <xref target="ISO.14496-22.2015"/>. </t>
<t>In addition, the following 6 characters could occur in the PostScript name but are
forbidden in fragments by <xref target="RFC3986"/>
and thus must be escaped: '"', '#', '\', '^', '`', '|'.</t>
<t>If (following un-escaping) this string matches one of the PostScript
names in the name table, that font is selected. For example, <spanx style="verb">#Foo-Bold</spanx>
refers to the font with PostScript name <spanx style="verb">Foo-Bold</spanx>
and <spanx style="verb">#Caret%5Estick</spanx> refers to the font with PostScript
name <spanx style="verb">Caret^stick</spanx>.
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.</t>
</section>
<section title="Registration Procedure">
<t>New font formats should be registered using the online form <xref target="Media-Type-Registration"/>.
RFC 6838 <xref target="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.</t>
<t>Note that new parameter sub-values may be defined in the future. If an
implementation does not recognize a sub-value in the
comma-separated list, it should ignore the sub-value and continue
processing the other sub-values in the list.</t>
</section>
<section title="Subtype Registrations">
<t>In this section the initial entries under the top-level 'font' media type are specified. They also
serve as examples for future registrations.</t>
<t>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 <xref target="W3C.CR-css-fonts-3-20131003"/>.
That specification is normative; the identifiers here are informative.</t>
<section title="Generic SFNT Font Type">
<t>
<list style="hanging">
<t hangText="Type name:">font</t>
<t hangText="Subtype name:">sfnt</t>
<t hangText="Required parameters:">None.</t>
<t hangText="Optional parameters:">
<list style="hanging">
<t hangText="1) Name: outlines">Values: a comma-separated subset of: TTF, CFF, SVG <vspace blankLines="1" />
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 <xref target="cff-wiki"/>,
and value SVG <xref target="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.</t>
<t hangText="2) Name: layout"></t>
<t>Values: a comma-separated subset of: OTL, AAT, SIL <vspace blankLines="1" />
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 containing one or more items, separated by commas.
Order in the list is not significant.</t>
</list></t>
<t hangText="Encoding considerations:">Binary.</t>
<t hangText="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. </t>
<t hangText="Published specification:">ISO/IEC 14496-22 "Open Font Format" (OFF) specification
<xref target="ISO.14496-22.2015"/> being developed by ISO/IEC SC29/WG11.</t>
<t hangText="Applications that use this media type:">All applications that are able to create,
edit or display textual media content. </t>
<t>
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
<list>
<t>uncommon combinations such as font/sfnt; outlines=sil which do not have a shorter type</t>
<t>cases where a new parameter value is registered</t>
<t>test cases, experimentation, etc</t>
</list>
</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">The TrueType fonts and OFF / OpenType fonts containing TrueType outlines should use 0x00010000
as the 'sfnt' version number.<vspace blankLines="1" />
The OFF / OpenType fonts containing CFF data should use the tag 'OTTO' as 'sfnt' version number.</t>
<t hangText="File extension(s):">Font file extensions used for OFF / OpenType fonts: .ttf, .otf<vspace blankLines="1" />
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.</t>
<t hangText="Macintosh file type code(s):">(no code specified)</t>
<t hangText="Macintosh Universal Type Identifier code:"><spanx style="verb">public.font</spanx> </t>
<t hangText="@font-face Format:">none.</t>
<t hangText="Fragment Identifiers">none.</t>
<t hangText="Deprecated Alias:">The existing registration <spanx style="verb">application/font-sfnt</spanx> is
deprecated in favor of <spanx style="verb">font/sfnt</spanx>.</t>
</list>
</t>
<t hangText="Person &amp; email address to contact for further information:">Vladimir Levantovsky (vladimir.levantovsky@monotype.com).</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">None</t>
<t hangText="Author:">The ISO/IEC 14496-22 "Open Font Format" specification is a
product of the ISO/IEC JTC1 SC29/WG11.</t>
<t hangText="Change controller:">The ISO/IEC has change control over this specification.</t>
</list>
</t>
</section>
<section title="TTF Font Type">
<t>
<list style="hanging">
<t hangText="Type name:">font</t>
<t hangText="Subtype name:">ttf</t>
<t hangText="Required parameters:">None.</t>
<t hangText="Optional parameters:">
<list style="hanging">
<t hangText="Name: layout">Values: a comma-separated subset of: OTL, AAT, SIL<vspace blankLines="1" />
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 font file, therefore,
this optional parameter is a list containing one or more items, separated by commas.
Order in the list is not significant.</t>
</list>
</t>
<t hangText="Encoding considerations:">Binary.</t>
<t hangText="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. </t>
<t hangText="Published specification:">ISO/IEC 14496-22 "Open Font Format" (OFF)
specification <xref target="ISO.14496-22.2015"/> being developed by ISO/IEC SC29/WG11.</t>
<t hangText="Applications that use this media type:">All applications that are able to create, edit or display textual media content.</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">The TrueType fonts and OFF / OpenType fonts containing TrueType outlines should use 0x00010000
as the 'sfnt' version number.</t>
<t hangText="File extension(s):">Font file extensions used for TrueType / OFF /
OpenType fonts: .ttf, .otf<vspace blankLines="1" />
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.</t>
<t hangText="Macintosh file type code(s):">(no code specified)</t>
<t hangText="Macintosh Universal Type Identifier code:"><spanx style="verb">public.truetype-font</spanx> </t>
<t hangText="@font-face Format:">truetype</t>
<t hangText="Fragment Identifiers">none.</t>
</list>
</t>
<t hangText="Person &amp; email address to contact for further information:">Vladimir Levantovsky (vladimir.levantovsky@monotype.com).</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">None</t>
<t hangText="Author:">The ISO/IEC 14496-22 "Open Font Format" specification is a
product of the ISO/IEC JTC1 SC29/WG11.</t>
<t hangText="Change controller:">The ISO/IEC has change control over this specification.</t>
</list>
</t>
</section>
<section title="OTF Font Type">
<t>
<list style="hanging">
<t hangText="Type name:">font</t>
<t hangText="Subtype name:">otf</t>
<t hangText="Required parameters:">None.</t>
<t hangText="Optional parameters">
<list style="hanging">
<t hangText="Name: outlines">Values: a comma-separated subset of: TTF, CFF, SVG<vspace blankLines="1" />
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.</t>
</list>
</t>
<t hangText="Encoding considerations:">Binary.</t>
<t hangText="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. </t>
<t hangText="Published specification:">ISO/IEC 14496-22 "Open Font Format" (OFF)
specification <xref target="ISO.14496-22.2015"/> being developed by ISO/IEC SC29/WG11.</t>
<t hangText="Applications that use this media type:">All applications that are able
to create, edit or display textual media content.</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">The TrueType fonts and OFF / OpenType fonts containing
TrueType outlines should use 0x00010000
as the 'sfnt' version number.<vspace blankLines="1" />
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.</t>
<t hangText="File extension(s):">Font file extensions used for OFF /
OpenType fonts: .ttf, .otf<vspace blankLines="1" />
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.</t>
<t hangText="Macintosh file type code(s):">(no code specified)</t>
<t hangText="Macintosh Universal Type Identifier code:"><spanx style="verb">public.opentype-font</spanx> </t>
<t hangText="@font-face Format:">opentype</t>
<!-- the @font-face format should be defined by reference to css3 fonts -->
<t hangText="Fragment Identifiers">none.</t>
</list>
</t>
<t hangText="Person &amp; email address to contact for further information:">Vladimir Levantovsky (vladimir.levantovsky@monotype.com).</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">None</t>
<t hangText="Author:">The ISO/IEC 14496-22 "Open Font Format" specification is a product
of the ISO/IEC JTC1 SC29/WG11.</t>
<t hangText="Change controller:">The ISO/IEC has change control over this specification.</t>
</list>
</t>
</section>
<section title="Collection Font Type">
<t>
<list style="hanging">
<t hangText="Type name:">font</t>
<t hangText="Subtype name:">collection</t>
<t hangText="Required parameters:">None.</t>
<t hangText="Optional parameters">
<list style="hanging">
<t hangText="Name: outlines">Values: a comma-separated subset of: TTF, CFF, SVG<vspace blankLines="1" />
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.</t>
</list>
</t>
<t hangText="Encoding considerations:">Binary.</t>
<t hangText="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. </t>
<t hangText="Published specification:">ISO/IEC 14496-22 "Open Font Format" (OFF)
specification <xref target="ISO.14496-22.2015"/> being developed by ISO/IEC SC29/WG11.</t>
<t hangText="Applications that use this media type:">All applications that are able
to create, edit or display textual media content.</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">The TrueType fonts and OFF / OpenType fonts containing
TrueType outlines should use 0x00010000
as the 'sfnt' version number.<vspace blankLines="1" />
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.</t>
<t hangText="File extension(s):">Font file extensions used for OFF /
TrueType and OpenType fonts: .ttc </t>
<t hangText="Macintosh file type code(s):">(no code specified)</t>
<t hangText="Macintosh Universal Type Identifier code:"><spanx style="verb">public.truetype-collection-​font</spanx> </t>
<t hangText="@font-face Format:">collection</t>
<t hangText="Fragment Identifiers:">See <xref target="fragments"/>.</t>
</list>
</t>
<t hangText="Person &amp; email address to contact for further information:">Vladimir Levantovsky (vladimir.levantovsky@monotype.com).</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">None</t>
<t hangText="Author:">The ISO/IEC 14496-22 "Open Font Format" specification is a product
of the ISO/IEC JTC1 SC29/WG11.</t>
<t hangText="Change controller:">The ISO/IEC has change control over this specification.</t>
</list>
</t>
</section>
<section title="WOFF 1.0">
<t>
<list style="hanging">
<t hangText="Type name:">font</t>
<t hangText="Subtype name:">woff</t>
<t hangText="Required parameters:">None.</t>
<t hangText="Optional parameters:">None.</t>
<t hangText="Encoding considerations:">Binary.</t>
<t hangText="Interoperability considerations:">None. </t>
<t hangText="Published specification:">This media type registration updates the WOFF specification
<xref target="W3C.REC-WOFF-20121213"/> at W3C.</t>
<!-- We should errata WOFF 1.0
to note that the registration has been changed. -->
<t hangText="Applications that use this media type:">WOFF is used by Web browsers, often
in conjunction with HTML and CSS.</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">The signature field in the WOFF header MUST
contain the "magic number" 0x774F4646 ('wOFF')</t>
<t hangText="File extension(s):">woff</t>
<t hangText="Macintosh file type code(s):">(no code specified)</t>
<t hangText="Macintosh Universal Type Identifier code:"><spanx style="verb">org.w3.woff</spanx> </t>
<t hangText="@font-face Format:">woff</t>
<t hangText="Fragment Identifiers:">none.</t>
<t hangText="Deprecated Alias:">The existing registration <spanx style="verb">application/font-woff</spanx> is
deprecated in favor of <spanx style="verb">font/woff</spanx>.</t>
</list>
</t>
<t hangText="Person &amp; email address to contact for further information:">Chris Lilley (www-font@w3.org).</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">None</t>
<t hangText="Author:">The WOFF specification is a work product of the World Wide Web
Consortium's WebFonts Working Group.</t>
<t hangText="Change controller:">The W3C has change control over this specification.</t>
</list>
</t>
</section>
<section title="WOFF 2.0">
<t>
<list style="hanging">
<t hangText="Type name:">font</t>
<t hangText="Subtype name:">woff2</t>
<t hangText="Required parameters:">None.</t>
<t hangText="Optional parameters:">None.</t>
<t hangText="Encoding considerations:">Binary.</t>
<t hangText="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. </t>
<t hangText="Published specification:">This media type registration is extracted from the
WOFF 2.0 specification <xref target="W3C.CR-WOFF2-20150414"/> at W3C.</t>
<t hangText="Applications that use this media type:">WOFF 2.0 is used by Web browsers,
often in conjunction with HTML and CSS.</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">The signature field in the WOFF header MUST contain the
"magic number" 0x774F4632 ('wOF2')</t>
<t hangText="File extension(s):">woff2</t>
<t hangText="Macintosh file type code(s):">(no code specified)</t>
<t hangText="Macintosh Universal Type Identifier code:"><spanx style="verb">org.w3.woff2</spanx> </t>
<t hangText="@font-face Format:">woff2</t>
<t hangText="Fragment Identifiers:">See <xref target="fragments"/>.</t>
</list>
</t>
<t hangText="Person &amp; email address to contact for further information:">Chris Lilley (www-font@w3.org).</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">None</t>
<t hangText="Author:">The WOFF2 specification is a work product of the World Wide Web
Consortium's WebFonts Working Group.</t>
<t hangText="Change controller:">The W3C has change control over this specification.</t>
</list>
</t>
</section>
</section>
</section>
</middle>
<back>
<references title='Normative References'>
<reference anchor="RFC2119" target="http://www.rfc-editor.org/info/rfc2119"><front><title>Key words for use in RFCs to Indicate Requirement Levels</title><author initials="S." surname="Bradner" fullname="S. Bradner"><organization/></author><date year="1997" month="March"/><abstract><t>In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t></abstract></front><seriesInfo name="BCP" value="14"/><seriesInfo name="RFC" value="2119"/><seriesInfo name="DOI" value="10.17487/RFC2119"/></reference>
<reference anchor="RFC3986" target="http://www.rfc-editor.org/info/rfc3986"><front><title>Uniform Resource Identifier (URI): Generic Syntax</title><author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee"><organization/></author><author initials="R." surname="Fielding" fullname="R. Fielding"><organization/></author><author initials="L." surname="Masinter" fullname="L. Masinter"><organization/></author><date year="2005" month="January"/><abstract><t>A Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. This specification defines the generic URI syntax and a process for resolving URI references that might be in relative form, along with guidelines and security considerations for the use of URIs on the Internet. The URI syntax defines a grammar that is a superset of all valid URIs, allowing an implementation to parse the common components of a URI reference without knowing the scheme-specific requirements of every possible identifier. This specification does not define a generative grammar for URIs; that task is performed by the individual specifications of each URI scheme. [STANDARDS-TRACK]</t></abstract></front><seriesInfo name="STD" value="66"/><seriesInfo name="RFC" value="3986"/><seriesInfo name="DOI" value="10.17487/RFC3986"/></reference>
<reference anchor='RFC6838' target='http://www.rfc-editor.org/info/rfc6838'>
<front>
<title>Media Type Specifications and Registration Procedures</title>
<author initials='N.' surname='Freed' fullname='N. Freed'><organization /></author>
<author initials='J.' surname='Klensin' fullname='J. Klensin'><organization /></author>
<author initials='T.' surname='Hansen' fullname='T. Hansen'><organization /></author>
<date year='2013' month='January' />
<abstract><t>This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice.</t></abstract>
</front>
<seriesInfo name='BCP' value='13'/>
<seriesInfo name='RFC' value='6838'/>
<seriesInfo name='DOI' value='10.17487/RFC6838'/>
</reference>
<reference anchor="W3C.CR-css-fonts-3-20131003" target="http://www.w3.org/TR/2013/CR-css-fonts-3-20131003"><front><title>CSS Fonts Module Level 3</title><author initials="J." surname="Daggett" fullname="John Daggett"><organization/></author><date month="October" day="3" year="2013"/>
<abstract><t>This CSS3 module describes how font properties are specified and how font resources are loaded dynamically. The contents of this specification are a consolidation of content previously divided into CSS3 Fonts and CSS3 Web Fonts modules. The description of font load events was moved into the CSS3 Font Load Events module. </t></abstract>
</front><seriesInfo name="World Wide Web Consortium CR" value="CR-css-fonts-3-20131003"/><format type="HTML" target="http://www.w3.org/TR/2013/CR-css-fonts-3-20131003"/>
</reference>
<reference anchor="ISO.14496-22.2015" target="http://standards.iso.org/ittf/PubliclyAvailableStandards/c066391_ISO_IEC_14496-22_2015.zip">
<front>
<title>Coding of audio-visual objects Part 22: Open Font Format</title>
<author>
<organization>International Organization for Standardization</organization>
</author>
<date month="10" year="2015" />
<abstract><t>ISO/IEC 14496-22:2015 specifies the Open Font Format (OFF) specification, the TrueType™ and Compact Font Format (CFF)
<xref target="cff-wiki"/>
outline formats, and the TrueType hinting language. Many references to both TrueType and PostScript exist throughout this document, as Open Font Format fonts combine the two technologies</t></abstract>
</front>
<seriesInfo name="ISO" value="Standard 14496-22" />
</reference>
<reference anchor="W3C.REC-WOFF-20121213" target="http://www.w3.org/TR/2012/REC-WOFF-20121213">
<front><title>WOFF File Format 1.0</title>
<author initials="J." surname="Kew" fullname="Jonathan Kew"><organization/></author>
<author initials="T." surname="Leming" fullname="Tal Leming"><organization/></author>
<author initials="E." surname="Blokland" fullname="Erik van Blokland"><organization/></author>
<date month="December" day="13" year="2012"/>
<abstract>
<t>This document specifies the WOFF font packaging format. This format was designed to provide
lightweight, easy-to-implement compression of font data, suitable for use with CSS @font-face rules.
Any properly licensed TrueType/OpenType/Open Font Format file can be packaged in WOFF format for Web
use. User agents decode the WOFF file to restore the font data such that it will display identically
to the input font.</t>
<t>The WOFF format also allows additional metadata to be attached to the file; this can be used
by font designers or vendors to include licensing or other information, beyond that present in the
original font. Such metadata does not affect the rendering of the font in any way, but may be displayed
to the user on request.</t>
<t>The WOFF format is not intended to replace other formats such as TrueType/OpenType/Open Font Format
or SVG fonts, but provides an alternative solution for use cases where these formats may be less
optimal, or where licensing considerations make their use less acceptable.</t>
</abstract>
</front>
<seriesInfo name="World Wide Web Consortium Recommendation" value="REC-WOFF-20121213"/>
<format type="HTML" target="http://www.w3.org/TR/2012/REC-WOFF-20121213"/>
</reference>
<reference anchor="W3C.CR-WOFF2-20150414" target="https://www.w3.org/TR/2016/CR-WOFF2-20160315/">
<front><title>WOFF File Format 2.0</title>
<author initials="V." surname="Levantovsky" fullname="Vladimir Levantovsky"><organization/></author>
<author initials="R." surname="Levien" fullname="Raph Levien"><organization/></author>
<date month="March" day="15" year="2016"/>
<abstract><t>Based on experience with WOFF 1.0, which is widely deployed, this specification was
developed to provide improved compression and thus lower use of network bandwidth, while still
allowing fast decompression even on mobile devices. This is achieved by combining a content-aware
preprocessing step and improved entropy coding, compared to the Flate compression used in
WOFF 1.0.</t>
</abstract>
</front><seriesInfo name="World Wide Web Consortium WD" value="CR-WOFF2-20150414"/>
<format type="HTML" target="https://www.w3.org/TR/2016/CR-WOFF2-20160315/"/></reference>
</references>
<references title='Informative References'>
<reference anchor="cff-wiki" target="https://en.wikipedia.org/wiki/PostScript_fonts#Compact_Font_Format">
<front>
<title>CFF</title>
<author><organization/></author>
<date/>
<abstract><t>Compact Font Format (also known as CFF font format, Type 2 font
format, or CFF/Type 2 font format) is
a lossless compaction of the Type 1 format using Type 2 charstrings.
The PostScript or Type 1 flavor of OpenType fonts, also called
OpenType CFF, contains glyph outlines and hints in a CFF table</t></abstract>
</front>
</reference>
<reference anchor="opentype-wiki" target="https://en.wikipedia.org/wiki/OpenType">
<front>
<title>OpenType</title>
<author><organization/></author>
<date/>
<abstract><t>OpenType is a format for scalable computer fonts. It was built
on its predecessor TrueType, retaining TrueType's basic structure and adding
many intricate data structures for prescribing typographic behavior. </t></abstract>
</front>
</reference>
<reference anchor="truetype-wiki" target="https://en.wikipedia.org/wiki/TrueType">
<front>
<title>TrueType</title>
<author><organization/></author>
<date/>
<abstract><t>TrueType is an outline font standard developed by Apple and Microsoft
in the late 1980s as a competitor to Adobe's Type 1 fonts used in
PostScript. </t></abstract>
</front>
</reference>
<reference anchor="svg-wiki" target="https://en.wikipedia.org/wiki/Scalable_Vector_Graphics">
<front>
<title>SVG</title>
<author><organization/></author>
<date/>
<abstract><t>Scalable Vector Graphics (SVG) is an XML-based vector image
format for two-dimensional graphics with support for interactivity and animation.
The SVG specification is an open standard developed by the World Wide Web
Consortium (W3C) since 1999.</t></abstract>
</front>
</reference>
<reference anchor="HTTP-Archive-Trends"
target="http://httparchive.org/trends.php?s=All&amp;minlabel=Nov+15+2010&amp;maxlabel=Feb+15+2015#perFonts">
<front>
<title>HTTP Archive trend analysis</title>
<author initials="D." surname="Kuetell" fullname="David Kuetell"><organization/></author>
<date month="March" year="2015"/>
<abstract><t>
Analysis of the Alexa top 480K websites, from Nov 15 2010 to
Feb 15 2015. It shows a steady rise in the number of sites using webfonts,
from 1% in 2010 to 50% in 2015.
</t></abstract>
</front>
</reference>
<reference anchor="Font-Media-Type-Analysis" target="http://goo.gl/zbDhUN">
<front>
<title>Web Font Media Type (mime type) Analysis 2015</title>
<author initials="D." surname="Kuetell" fullname="David Kuetell"><organization/></author>
<date year="2015"/>
<abstract><t>
Adoption rate of registered media types for TrueType, OpenType and WOFF
fonts (in the application tree) is extremely low, ranging from 1% to 0.07%.
In practice, a wide range of unregistered types is observed, including significant
use (90.8%, for WOFF) of the non-existent font top-level type. This contrasts
with more than 90% adoption rate for PNG, GIF, and JPEG which have intuitive
Media Types in the image tree.
</t></abstract>
</front>
</reference>
<reference anchor="WG-tlt" target="https://www.w3.org/Fonts/WG/track/actions/164">
<front>
<title>ACTION-164: Bring widely used top-level-type to w3c-ietf liaison</title>
<author><organization>W3C</organization> </author>
<date year="2015"/>
<abstract><t>Following discussion at several phone calls and face to face meetings,
the W3C WebFonts Working group decided that the widely used but unregistered font/* top-level type
should be standardized, and created this action item to track it.</t></abstract>
</front>
</reference>
<reference anchor="Media-Type-Registration" target="http://www.iana.org/form/media-types">
<front>
<title>Application for a Media Type</title>
<author><organization>IANA</organization></author>
<date/> <!-- not sure what date to put for a form -->
<abstract><t>Application form for new Internet Media Types.</t></abstract>
</front>
</reference>
</references>
</back>
</rfc>