They contain a number of self-defining fields, called text units.
Implementations are expected to ignore any text unit information not relevant to the receiving system.
It contains information identifying the sender: node (host), timestamp, and user id, the length of the control record segments, and the target (receiving) node and user id.
It may optionally contain a request for acknowledgement of receipt, the version number of the data format, the number of files in the transmission, and a "user parameter string."
Bytes 8-11 contain the big-endian binary number of the file to which this record applies.
The text units identify the file's organization (INMDSORG: sequential, partitioned, etc.
), its fixed of maximum record length (INMLRECL), its record format (INMRECFM: fixed, variable, etc) the approximate size of the file (IBMSIZE), and the utility program name(s) (INMUTILN).
It contains the file's organization (INMDSORG), its record length (INMLRECL), its record format (INMRECFM), and the file size (IBMSIZE).