Jacques.dat is the largest custom level set ever made, with 986 levels in its full form. The start of the making of this set dates to 2003.
As it may be expected that a fair quantity of a set this large are average to poor levels, Jacques released several versions of a leaner and much better set, containing what he chooses to be the best levels in the set. This set, officially named Jacques' Scrapbook 1, though listed as JacquesS1.dat in the directory, is composed of 233 levels.
The set was planned to have 1,000 levels, however Jacques hasn't got around to filling in the remaining 14 levels.