The 'ISRT' (Insert) function code is used to add new records to a GSAM dataset. DL/I uses abbreviated 4-character codes for its functions, making ISRT the correct form rather than INSERT or other variations.
In IMS DL/I (Data Language/I), the call function used to insert a new segment/record into the database is ISRT. IMS call codes are four-character mnemonics, and ISRT is the standard one for insert operations, distinct from other DL/I calls like GU (Get Unique), GN (Get Next), or REPL (Replace).