Reading Tapes
When you create a tape file using AMSERV under CMS, CMS writes a label file preceding each output file. When CMS AMSERV reads this file, it checks the HDR1 and VOL1 labels using the LABELDEF command you provide before it reads the data file. If you want to read the tape on a real OS/VS system, however, you must use either LABEL=SL or LABEL=(2,NL) as a parameter on the data definition (DD) card for the tape.
If you are creating a tape under OS/VS access method services to be read by CMS AMSERV, you must be sure to create the tape using standard labels so that CMS can read it properly. CMS cannot read a tape created with LABEL=(,NL) on the DD card.
For CMS to read this tape for any other purpose (for example, to use the MOVEFILE command to copy it), you must remember to forward space the file past the tape mark before beginning to read it.