Hi Polimom,
A stamp with "AQ" at the top is usually referred to by its letters at the bottom, "QA".
This is because when corner letters were introduced they were only at the bottom of each stamp.
Quote:
SG's Vol 1 Specialized says, "The letters were as usual, AA to AL in the top row and so on down to TA to TL in the bottom row (quoting lower corner letters only)."
Here, SG means:
"The letters were as usual, AA to AL
at the bottom of each stamp in the top row and so on...".
So the QA stamp (with AQ at its top) is from row Q and column A which is fine.