In creating the Key, how do you mark Scantron Forms for true and false questions?

I have used Scantron Forms to grade multiple choice questions on test, but would like to try using it for true and false also.In creating the Key, how do you mark Scantron Forms for true and false questions?
It depends on the type of scantron, I'm sure, but couldn't you just use A/B=true/false?