A Blorb file contains all the graphics and sound files needed for a game. It can also contain the Z-code for the game as well, but does not need to: The game could also be distributed as separate Z-code and Blorb files. If you try to load a Blorb file into Windows Frotz 2002 that does not contain Z-code, it will ask you to load the appropriate Z-code file into the interpreter instead.
Blorb files can contain JPEG and PNG graphics files, AIFF sound samples, and MOD and SONG music files. Windows Frotz 2002 supports all of these formats, including transparency, opacity and gamma correction for PNG graphics. Windows Frotz 2002 also supports Kevin Bracey's extensions to the Blorb format for Infocom's V6 games.