Type name:  font

Subtype name:  ttf

Required parameters:  None

Optional parameters:

   Name: layout  
   
   Values: a comma-separated subset of OTL, AAT, and 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 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 Section 3 of RFC 8081, 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.

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 and .otf

      Typically, the .ttf extension is only used for fonts containing
      TrueType outlines, while the .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

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.