Adaptec's CL3 files in Easy CD Creator were "project" files. They are only a list of the files or songs you wanted written to your disc, but they do not contain the actual songs or files. Also, CL3 files will only work for version 3 of the application and will not work in other versions. Reason is Adaptec/Roxio named files extensions by the version of the application.
CL4=ECDC 4, CL5=ECDC 5 and so on.