Matrix Rassilon's universe

In one of the palimpsest universes observed by Omega, Rassilon continued to rule Gallifrey from deep within the Matrix. Omega told the Infinity Doctor of this, clarifying that what he saw was, rather than a parallel universe, a version of his own reality. (PROSE: The Infinity Doctors)

Relation to other realities
Rassilon's status as a Matrix Lord was recorded in the Scrolls of Gallifrey (PROSE: The Legacy of Gallifrey) and was part of a sequence of events from the life of the Fifth Doctor (COMIC: The Tides of Time) up to the Eighth Doctor. (COMIC: The Final Chapter)