The TCOMMIT command marks the end of a transaction or sub-transaction and decrements $TLEVEL. If TCOMMIT marks the end of a transaction (decrements $TLEVEL to zero), it invokes a COMMIT, which makes the database updates performed by the transaction generally available. A TCOMMIT issued when no transaction is in progress ($TLEVEL=0) produces an error.

The format of the TCOMMIT command is:


For an example of the use of the TCOMMIT command, see Chapter 5: “General Language Features of M.