The Surveillance System was developed after the Mark IX TARDIS. This system allows a TARDIS to continually collect and store all data observed by its sensors. This data was then uploaded to the Matrix. Using the Matrix's processing abilities this data could be used to render visual and audio images for events occurring anywhere within its collection field (at least several miles) even if the event in question was deep underground. Despite not becoming available till after the Mark IX Refit, this function was retroactively installed in all capsules running earlier refits by Gallifreyan technicians at the first available opportunity.
The following color code is used:
- Black: For information from the TV Series, including Dimensions in Time, and 1996 TV Movie.
- Blue: For information from the Novels and Audios including Target, Virgin, BCC, and Big Finish.
- Green: For information from 'licensed' reference sources such as the Technical Manual, Doctor Who Magazine, and the Role Playing Games.
- Red: For information from unofficial sources -The Faction Paradox series, behind the scenes interviews, author's speculation, and popular fan belief.
The TARDIS Technical Index is copyright Will B Swift.