Example: Record format *V

This is an example of record format *V, which consists of a graphic with an explanation.

Variable-length, deblocked, unspanned (*V).

Figure 1. Variable-length, deblocked, unspanned (*V)
This graphic displays two
blocks and a record. The two blocks are named Block 1 and Block 2, while the
record is named Record A. Block 1 is comprised of XX YY and a Record A. Block
2 is comprised of XX YY and a Record B. Record A is comprised of VV WW and
Record A data. Record A and Block 1 both point toward each other.

This graphic displays two
blocks and a record. The two blocks are named Block 1 and Block 2, while the
record is named Record A. Block 1 is comprised of XX YY and a Record A. Block
2 is comprised of XX YY and a Record B. Record A is comprised of VV WW and
Record A data. Record A and Block 1 both point toward each other.

XX and YY make up the BDW. XX is the length of the record plus the length of the BDW (4 bytes). YY represents currently reserved fields and must be 00. XX should be the actual length of the data block that is written.

Record A has its own mapping by including the RDW. VV and WW make up the RDW. VV is the length of the record plus the length of the RDW (4 bytes). WW are currently reserved fields and must be 00. VV should be the actual block length (the value in XX) minus 4 bytes (size of BDW). i5/OS™ will pad blocks to make the 18-byte block limit. This occurs if the record data is less than 10 bytes (10 bytes plus 8 bytes of header information is the 18-byte block limit). i5/OS will pad the block with a byte of X'80' followed by bytes of X'00'.

Note: Record-format *V tapes created by i5/OS that contain record data that is less than 10 bytes are not directly compatible with OS/390^® and z/OS^®. To process these tapes with OS/390 and z/OS, you need to code RECFM=VS or RECFM=VBS on the DD statement even though the records are not spanned. This allows OS/390 and z/OS to read the tapes without error.