HP E4418B Programming Manual page 438

Query
UNIT[1|2]:POWer?
The query returns the current setting of the measurement units.
Query Example
HP E4418B/E4419B Programming Guide
UNIT2:POW?
UNIT[1|2]:POWer <amplitude_unit>
This command queries which
measurement units are being used
on the lower window. In addition,
for the HP E4419B this command
also queries the default units for
any relevant SENSe2 command.
UNIT Subsystem
13-5