The Unofficial Doom Specs is the title of a text document by Matt Fell which gives details for many of the of Doom. Most usefully, the specs give detailed information about the structure of WAD files and the various different types of resources they contain. The specs cover: Documentation on several pieces of data are conspicuously absent from the file: * Detail on the .MUS format used for Doom's music, other than the header * The format of PC speaker sound effects