what is the meaning of gain control range in power amplifier

hi
what is the meaning of gain control range in power amplifier in rf field.
plz describe the definition

in some power amps or the driver amplifiers , u can change the gain of the amplifier
it is VGA , and there are now some PA , have two gain modes high gain an low gain

so the gain control range as i think is the range u can change the gain of ur PA

khouly