Tables

The SFNT font format is table-based. Each table is identified by a 4-byte tag, usually all uppercase or all lowercase ASCII alphabetic characters. Notable examples are the OS/2 and the CFF (note the trailing space!) tables.

A table is a binary data structure. @pdfa-lab/fontkit loads this data structure lazily. Initially, when a font is loaded, the library only checks which tables are present in the font table directory. They get loaded and decoded, when they are first accessed.

The base class of all font formats TrueTypeFont therefore defines all tables as nullable, and robust code should always check for a particular table's existence, before trying to access its properties.

It should be mentioned that some large tables are not fully decoded when accessed. Parts of these tables, usually bulk data, may be loaded lazily, when the corresponding substructures are accessed.