I.M. Foreman's One-Species Nongenetically Engineered Travelling Show is a complex space-time event. It is similar to, although not like, a TARDIS.
Piloting and Travel
I.M. Foreman programmed the show's course by meditating and communicating telepathically with it.
It is a space-time vessel but it has no extra-dimensional connections. It moves through space and time by retroactively building a site and disguising itself before/during/as it moves there. This process takes years.
It is not designed for instantaneous (or even fast) travel, unlike a TARDIS. Unlike most TARDISes, the show can (and does) travel back into the Dark Time. (EDA: Interference - Book One, Interference - Book Two)
Effects the show has on space time
A by product of this is that it sometimes knocks dents in space-time which lures other space-time travellers to the site. It brought Faction Paradox, the Remote, and the Third Doctor and Sarah Jane Smith to the planet Dust. It is thought that it may have brought the First Doctor and Susan to Earth, 76 Totter's Lane, 1963.