Setting 2H Lines?

[Frank Costanza]

Random question as I'm not knowledgeable enough but know many of you are.....How are 2H lines set, so quickly? I assume it's a pure quantitative thing that takes the closing game line, the margin at the half, uses a simple algorithm and spits out a 2H spread? Obviously any 1H (really major) injuries could yield a line to come off the boards as well.

I'll hang up and listen. Thanks.