From NATOPS (applies to Rhino, but I guess relevant to Classics as well)
2.11.3.2 Cage/Uncage Button.
The cage/uncage button is located on the rear inboard side of the right throttle. In NAV master mode and A/G master mode (AUTO delivery), the cage/uncage button is used to cage and uncage the velocity vector. Depending on master mode and TDC priority assignment, the cage/uncage button can be used to (1) cage/uncage weapons, (2) command a radar STT, (3) toggle between weapon modes, or (4) reset sequenced HARM targets.
Also: