Here it is from the NCAA rule book. You can download the NCAA rulebook here.
http://www.ncaa.org/library/rules/20...ball_rules.pdf
Eligibility to Touch Legal Pass
ARTICLE 3. Eligibility rules apply during a down when a legal forward
pass is thrown. All Team B players are eligible to touch or catch a pass.
When the ball is snapped, the following Team A players are eligible:
a. Each player who is in an end position on his scrimmage line and who is
wearing a number other than 50 through 79 (A.R. 7-3-3-I).
b. Each player who is legally positioned as a back wearing a number other
than 50 through 79.
c. A player wearing a number other than 50 through 79 in position to
receive a hand-to-hand snap from between the snapper’s legs.
Eligibility Lost by Going Out of Bounds
ARTICLE 4. No eligible offensive receiver who goes out of bounds during
a down shall touch a legal forward pass in the field of play or end zones or
while airborne until it has been touched by an opponent or official (A.R.
7-3-4-I-III).
Exception: This does not apply to an eligible offensive player who
attempts to return inbounds immediately after being blocked out of bounds
by an opponent (A.R. 7-3-4-IV).
Eligibility Gained or Regained
ARTICLE 5. When a Team B player or an official touches a legal forward
pass, all players become eligible (A.R. 7-3-5-I).