Unlabeled and Nonstandard Labeled Tapes
You define an unlabeled tape with the DTFMT parameter FILABL=NO. The tape file is processed as having no labels.
You define a nonstandard labeled tape with the DTFMT parameter FILABL=NSTD. You must also provide a routine to process your nonstandard labels in the LABADDR=parameter of the DTFMT. Tape processing in CMS for these files is the same as it is under VSE.