Deadlock seal

From Tardis Wiki, the free Doctor Who reference

A deadlock seal was a form of lock or a device added to a lock that was almost impregnable. It was more secure than most locks. The Doctor's sonic screwdriver could not open deadlock seals by itself, (TV: Bad Wolf) however these locks could be keyed to specific sonic devices such as a sonic pen, which would allow the key to break these seals. (TV: Partners in Crime)

Features

Deadlocking made locks more difficult to open, at least with sonic devices. More sonic devices could be used in concert to break deadlock seals. (TV: Partners in Crime) Additional deadlocking could be applied, from double (TV: Voyage of the Damned) to triple (TV: Partners in Crime, GAME: TARDIS).

It was possible to create deadlock seals with a sonic device. The Doctor "locked" several things during his travels, particularly the controls of his TARDIS, which even the Master could not unlock. (TV: 42, Utopia, The Sound of Drums, Last of the Time Lords, TV: Invasion of the Bane)

Deadlocking did not make glass unbreakable. (TV: The Poison Sky) It did, however, make metal incapable of being melted, or at least heated, and could prevent cords and doors from being separated or opened physically. (TV: The Time of Angels)

Notable uses