Introduction
TrueType font files are made up of a number of tables, some mandatory (such as the 'glyf' table containing glyph outlines), others optional (like the 'kern' table). TrueType was designed this way to make the format extensible. Microsoft has taken full advantage of this in defining tables for the TrueType Open and, with Adobe, the OpenType initiative.

You'll need the TrueType Specification if you're involved with any of the following:

• Making special modifications to TrueType fonts beyond the abilities of your current font editor
• Writing a program to generate TrueType font files
• Writing a program to interpret TrueType font files (although both Windows and the Macintosh have GDI function calls that retrieve much important data)

TrueType Specifications

• The TrueType font file
  Apple's current specs. Contains full specifications of all TrueType GX tables, as well as standard TrueType tables.

• TrueType v1.66 and TrueType Open
  Microsoft's complete specs in MS Word format.

• OpenType 1.0
  Online specs from Microsoft, all in HTML including standard TrueType tables.

• TrueType 1.0
  Online at the Web Library of Scott W. Adkins. This is an HTML version of the specification originally distributed by Microsoft in Word format.

• The Font Manager
  in the non-GX Macintosh.

• Type 42 fonts [PDF file]
  These are TrueType fonts with a PostScript "wrapper", intended for downloading to those PostScript Level 2 printers that have a built-in TrueType rasterizer. The drivers for such printers should automatically create Type 42 fonts for rasterizing by the printer.

• Apple TrueType Font Format Specification 1.0
  (APDA #M0825LL/A). This is the original printed specification.

See also

• Apple Fonts Site
  for developers of TrueType and TrueType GX fonts

• Developing TrueType fonts
  according to Microsoft