The Fourth Doctor believed that coordinates suggested a simple geometric position, combined in three-dimensional Cartesian vector, and noted that things were more complicated with ten dimensions, as the TARDIS required. (AUDIO: The Memory Thieves [+]Loading...["The Memory Thieves (audio story)"]) However, other accounts suggested that TARDISes used space-time coordinates. (TV: The Pirate Planet [+]Loading...["The Pirate Planet (TV story)"], Castrovalva [+]Loading...["Castrovalva (TV story)"], Knock Knock [+]Loading...["Knock Knock (TV story)"], et al.)
Jack Harkness believed that Project Indigo had no coordinates. (TV: The Stolen Earth [+]Loading...["The Stolen Earth (TV story)"])
Planets were located according to galactic coordinates. (TV: Pyramids of Mars [+]Loading...["Pyramids of Mars (TV story)"], Full Circle [+]Loading...["Full Circle (TV story)"])
The Doctor's TARDIS and the Space-Time Manipulator operated using space-time coordinates and chrono-spatial coordinates. (TV: Knock Knock [+]Loading...["Knock Knock (TV story)"], Regeneration [+]Loading...["Regeneration (TV story)"])