Isomorphic controls

Isomorphic controls were security settings used in devices to prevent anyone other than the predetermined owner from accessing them.

One known device which had isomorphic controls was the Master's laser screwdriver. The Doctor attempted to use it to overpower the Master, but was laughed at by the Master when he could not. (DW: Last of the Time Lords)

The Doctor claimed that the TARDIS' controls were isomorphic: that is, only he could operate them. (DW: Pyramids of Mars) In fact, it was only a bluff. (BFA: The Bride of Peladon)