Game Used Footballs Pen Marking

[schubert1970]

Anyone know the significance of the pen marking on the laces of game NFL game used balls? I've attached a few examples.

[BULBUS]

The ref inspects the footballs before the game and mark them if all is ok. I believe each ref has their own mark, symbol, number, ect.

[schubert1970]

Txs Chris!

[GoGators]

Does that apply in college too?

I've noticed the same on my game-used Florida Gators football:
http://www.americanmemorabilia.com/pics/68223_01_lg.jpg