Relative Continuum Displacement Zone

A Relative Continuum Displacement Zone was effectively a hole in time. It could be caused by improperly sending an object back in time. If it destabilised, it could cause a "direct continuum implosion", which could destroy entire planets. (TV: Image of the Fendahl)

The Time Lords had set their TARDISes to detect Relative Continuum Displacement Zones, in order to prevent damage in time. When the Arkive tried to send an allohistorical lure back in time, it created a Relative Continuum Displacement Zone around Saturn. The Doctor's TARDIS was attracted to it and refused to leave until the problem was solved. (PROSE: The Wheel of Ice)

The Doctor's TARDIS was again dragged towards a Relative Continuum Displacement Zone by Dr Fendelman's experiments on Eustace with his time scanner. (TV: Image of the Fendahl)

Behind the scenes
A relative continuum displacement zone was mentioned in the BBV Productions audio The Pattern.