Motorola R-2550 Programming Reference Manual page 209

MZO (R-2600) (LPA option only)
Description:
Command Syntax: MZO
Caution:
Motorola Communications Analyzer
The MZO command Zeroizes the Thermal Power meter.
Before
zeroing the Thermal Power Meter, be sure the power head is attached to the
connector at the left rear of the analyzer, and that no RF power is applied to the head.
Zeroize Thermal Power Meter