If we're going with DC or IS to avoid the non-narrative IF, then we have to go with the proper TARDIS, too. Wikia can call it what they like, but the logo etc. needs to be TARDIS Data Core.
"The term radar has since entered English and other languages as the common noun radar, losing all capitalization." Radar is a word in it's own right, whereas TARDIS, I believe, is not - it is only an acronym.