Type name: font Subtype name: sfnt Required parameters: None Optional parameters: 1) Name: outlines Values: a comma-separated subset of True Type Font (TTF), Compact Font Format (CFF), and SVG This parameter can be used to specify the type of outlines provided by the font. The value "TTF" shall be used when a font resource contains glyph outlines in TrueType format, the value "CFF" shall be used to identify fonts containing PostScript/CFF outlines [cff-wiki], and the 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, Apple Advanced Typography (AAT), and 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 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 RFC 8081's 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 an 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; layout=sil" that 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 the 'sfnt' version number. File extension(s): Font file extensions used for OFF / OpenType fonts: .ttf and .otf Typically, the .ttf extension is only used for fonts containing TrueType outlines, whereas the .otf extension can be used for any OpenType/OFF font, and either can be used with the 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.