I am controlling several PNAs (N5222A, N5230C, E8361C) using GPIB/SCPI and only the N5222A is able to be upgraded to the A.09.90 firmware. I am able to determine the last modified date of a file on N5222A since the MMEM:DATE? function is built into the newer firmware, however, this was not in the A.09.42 version. Is there an alternative to this in the older version that performs the same function? I have yet to come across anything. Thank you.