Leeway
From Tardis Wiki, the free Doctor Who reference
When the Tenth Doctor used his sonic screwdriver to fuse the TARDIS' coordinates, he ostensibly restricted the Saxon Master to travel between the year 100,000,000,000,000 and the last place the TARDIS landed in 2008, but later admitted that a "little leeway" of eighteen months existed. (TV: The Sound of Drums)
