Matrix door
A Matrix door, or Matrix entrance door, (PROSE: Interstitial Insecurity) was a method of physically entering the Matrix on Gallifrey, (TV: The Ultimate Foe) a real world interface (AUDIO: Ascension) as opposed to merely connecting one's mind to the Matrix. (TV: The Deadly Assassin)
The sensation of passing through a Matrix door felt like being "scanned". (AUDIO: Lies) At least 14 doors existed around the Capitol, though there could have been any number of doors as K9 was able to create them (AUDIO: Ascension) and Coordinator Narvin had a "Matrix portal activator" that allowed him to open one in his office. (AUDIO: From the Flames)
Notable Matrix doors included the legendary Seventh Door outside the courtroom on Space Station Zenobia, (TV: The Ultimate Foe) the Eighth Door onboard the Time Station, (AUDIO: Neverland) and the Twelfth Door through which the Daleks invaded Gallifrey from the Matrix. (AUDIO: Ascension) A fluctuating Matrix access door also existed within the Vaults on Gallifrey. (AUDIO: Lies)
The Valeyard hid another matrix door on the mudball planet orbiting Etarho, using it to escape the particle disseminator trap left for the Sixth Doctor and Inquisitor Darkel. (AUDIO: Trial of the Valeyard)
