This is the format for resources of type MUSICRES (these have the extension .mod in the original source). If the first 3 characters are 'CDA', from the next character to the first nul char, or 3 characters after the first period (whatever comes first) is used as a filename with aif audio data to play. (CDA stands for CD-audio. The source code mentions 'red book', but it's not (red book is the standard for audio CD's)). The rest of the file (just a few more chars) seems to be garbage. If the first 3 characters are something else, the entire file (including the first 3 characters) are used as a MOD file. (As the mod file uses those char as the title of the song, a mod file with the title beginning with 'CDA' will go wrong). Initial version of this file 2002-10-26 by Serge van den Boom.