The technique used to add format-V and -U records with keys depends on whether records are located by indirect addressing or by a cross-reference table. If indirect addressing is used, you must at least initialize each track (write a capacity record) even if no data is actually written. That way the capacity record shows how much space is available on the track. If a cross-reference table is used, you should enter all the actual input and initialize enough succeeding tracks to contain any additions that might be required.

To add a new record, use a relative track address. The system examines the capacity record to see if there is room on the track. If there is, the new record is written. Under the extended search option, the record is written in the first available area within the search limit.