HP 83751A Programming Manual page 154

Programming Commands
Power Subsystem
Query Syntax
Sets and queries the state of the RF attenuator coupling switch. Programming
a specified attenuation sets POWer:AT%nuation:AUTO OFF.
ON
OFF
*RST value is ON.
2-48
POWer:ATTenuation:AUTO ONlOFFlllO
POWer:ATTenuation:AUTO?
insures that the amplitude level of the ALC is kept within optimal
the attenuator setting is set to the value of POW:ATT and left
there.