How do I change the power meter's system model number (E4418A or E4419A) to be the same as the physical model number (E4418B or E4419B) ?

To change the power meter's system model number from E4419A to E4419B and from E4418A to E4418B, use the following SCPI command:
serv:vers:proc "C"
serv:vers:syst "2"