User Guide

FontLab 4
634
OpenType Tables
OpenType fonts consist of multiple tables. Every table is identified by a
tag, which is a combination of up to 4 characters.
3 tables are “responsible” for the OpenType features:
GDEF
Glyph definition table. Contains information about font glyphs, including
their type (simple, mark or ligature), cursive-attachment points and
position of the caret inside the ligature character.
GSUB
Glyph substitution features
GPOS
Glyph positioning features
Other tables may exist in OpenType fonts, for example the BASE table that
defines different baseline positions for non-Latin scripts, but FontLab
cannot work with these tables yet.
Please note that the presence of any one of these tables makes a TrueType
font an OpenType font.