The TSSINSTX entry to check inbound commands is the COMMAND entry.
It is described as it follows within the TSSINSTX:
TO INTERPRET TSS COMMAND USAGE TXACTGTS CAN BE USED TO DETERMINE THE MACHINE OF ORIGIN WHEN CPF IS IN USE.
TXACTGTS = 0 INDICATES THE COMMAND ORIGINATED ON THE LOCAL MACHINE.
IF TXACTGTS > 0, THEN IT POINTS TO THE 8-CHAR NODE NAME OF THE ORIGINATING MACHINE.