Zero time

From Tardis Wiki, the free Doctor Who reference

Zero Time was an alternative form of time developed by the Enemy, in order to avoid the detection of the Great Houses.

The Enemy discovered that by moving their timeships first into zero time and then back into real time they would avoid dragging along bits and bobs of prior time periods, meaning that the Gravity Spiders looking for these discontinuities would come up empty.

However, the residual traces of zero time would later be analysed by the Houses to determine the technical specifications of Enemy time ships, as well as their recent histories, in one of the first real technology successes of the Houses in the first 50 years of The War.

Zero time was also used in an attempt to access Utterlost, though these pathways were cutoff as well, eventually. (PROSE: The Book of the War)