Documentation for Monotype's OpenType Layout Source File Format
Beginning in 1999 Monotype needed the ability to create, view and debug fonts with OpenType Layout tables. A text representation of the OpenType tables (GSUB, GPOS, and GDEF) was created that follows the actual structure of the tables so that these source files could be compiled into binary format and vice versa. This document describes the format of such source files. With appropriate tools such files can be converted to binary data and inserted into fonts.
To view the documentation open http://monotype.github.io/OpenType_Table_Source/ in a browser.