In Figure 1, an indexed sequential data set with variable-length records is updated directly with transaction records on tape. The transaction records are of variable length and each contains a code identifying the type of transaction. Transaction code 1 means that an existing record is to be replaced by one with the same key; code 2 means that the record is to be updated by appending additional information, thus changing the record length; code 3 or greater means that the record is to be updated with no change to its length.

For this example, the maximum record length of both data sets is 256 bytes. The key is in positions 6 through 15 of the records in both data sets. The transaction code is in position 5 of records on the transaction tape. The work area (REPLAREA) size is equal to the maximum record length plus 16 bytes.