"Offside" on the offense?
 

From a four-sport official that doesn't work football:

How often, if at all, do you call offside on the offense? If a offensive player is lined up in the neutral zone/beyond the line of scrimmage, do you use the term "offside," or go with "illegal procedure" or something else?

NFHS: It's encroachment.

There's no such thing as offside or illegal procedure in NFHS rules.

It's also encroachment in NCAA rules.

Oddly enough, encroachment in NCAA is a dead-ball foul, while defensive offside is a live-ball foul.

In FED, both offensive encroachment and defensive encroachment are dead-ball fouls.

But to answer your question... it's almost never called, because it almost never happens. But, interestingly enough local college game here last year ended on a 10-second runoff due to offensive encroachment.

Its never called because the wings tell the player to get back and if he gets back, there's no real advantage gained.

Preventive officiating normally takes care of encroachment. Usually the problem arises on offense when the o-lineman are in a two point stance to check the play call from the sideline and then move downward into the 3 point stance and go down into the neutral zone. On defense it usually gets called on interior lineman who can't/won't hear them being told to get out of the NZ.

As a former offensive lineman, I can tell you there's no advantage gained by offensive linemen encroaching on the NZ... in both pass and run blocking, I'd like the extra space to give myself time to maneuver into position between the snap and initiating the block on the defender. It's one of the reasons my least-favorite position was center, and one of the reasons why most o-line alignment problems are from players lining up too far back from the NZ.

D-linemen, on the other hand, usually want to get as close to the NZ as possible, because it puts them that much closer to the QB/runner and helps them disrupt the blocker before he can get his initial steps completed.

As a line coach I can tell you that sometimes there would be an advantage for an OL to line up in the neutral zone. There are tactical reasons for lining up as far back as possible, and also for lining up as far forward as possible, and different systems of offense produce different preferences on that. If you could line up in the neutral zone, you could get a better angle on blocks against DL on either side of you. And that's to say nothing of the advantages the offense could gain if some of their players could line up several yards in advance of the neutral zone!