1. A book of instructions and specifications of a piece of equipment or system. User Manual, Owner's Manual, Operator's Manual, Installation Manual. RTFM
2. A human operated, as opposed to automatic, action. Some lighting consoles allow both manual and timed fades. Any non-programmed action.
3. In the olden days (1960s-'70s), dimmer, resistance
and dimmer, autotransformer
systems were called manual; those newfangled SCR
dimmer systems were called remote or preset