The input should be a disk or tape file without a VICAR label.
The input dataset contains logical records of length 1024 bytes. When the input is on tape, the records are typically blocked, with up to 31 logical records per physical record. When the input is from tape, the value of BLOCK should be specified as the bytes per physical record on tape, divided by 1024. The default value of 1 is usually the appropriate value for disk input files.