In one game in Week 7, a flag was called for a receiver lining up at the line of scrimmage? Are they supposed to line up behind it? – Lisa B
Without more information, I can not give you much of an answer. I know that in one of the games that I was watching, a receiver was flagged for being on the line outside of the tight end who was also on the line. In this case, the Tight End was considered to be "covered up" and this is a foul for illegal formation (or illegal procedure). In this instance, the wide receiver should have been off the line.
If you can give me more information on exactly what occurred, I will be glad to give you more of an answer.

