Dead Ball foul or Roughing or neither

[Adam]

It seems to me the confusion lies with where to draw the line on ignoring dead ball contact.

Examples (for my own clarification as a rookie FB official):
1. The ball is snapped, but the HL has an encroachment foul on the defense. The whistle is late, and immediately after the whistle, A67 holds B99. Ignore the DB contact?

I think so.

2. The ball is snapped, but the U has a snap infraction. Immediately after the whistle, B97 grabs the facemask of an offensive lineman. Ignore the DB contact?

I doubt it.

3. The ball is snapped in a punt formation, but the LJ has a false start on the wing. Immediately after the snap and before the whistle, the B99 roughs the snapper. Ignore the DB contact?

I don't know.

In basketball, DB contact is ignored if it's not intentional or flagrant, and I think I'm trying in vain to apply that standard to football.