googled it.. here is the result
Encroachment is when a defensive player lines up in the neutral zone or gets
caught in the neutral zone at the snap.
Offside is when 1) a defensive player is accross the line of scrimmage at the
snap or 2) when an offensive player lines up acros the line of scrimmage.
False start is when an offensive player makes an illegal movement before the
snap of the ball.
