I didn't found any data from FIFA Technical Study Group, this Wikipedia Link states:
Statistics for assists made by players may be kept officially by the organisers of a competition, or unofficially by, for example, journalists or organisers of fantasy football competitions. Recording assists is not part of the official Laws of the Game and the criteria for an assist to be awarded may vary.
But NCAA Official Soccer Statistics Rules section 5 article 1 states:
Article 1. A player is credited with an assist when he makes, in
the opinion of the statistician, a pass contributing directly to a goal.
Not more than two assists may be credited on any one scoring
play. Each assist shall count one point in the player’s statistical
If a scoring play consists of two consecutive passes without
a defender gaining control of the ball, two assists may be
awarded, provided the second player does not have to elude
a defender to make the final pass. Both passes must have a
direct influence on the outcome of a goal scored. If the second
player needs to elude a defender before passing to the
goal-scorer, credit only that assist.
Link to NCAA Soccer Statisticians' Manual