Hi Mark,
I'm sure someone can explain this better than me, but since I started this thread...
ASL's or "American Semi-Longbows" are D-style bows, which people often call Hill-style bows. The limbs can either be backset, straight-end, or string-follow.
When unstrung, a straight-end bow will have limbs that are, well, straight. A backset bow will have limb tips that are forward (i.e., ahead of the riser), and a string-follow will have tips that are backward (i.e., set behind the riser).
I hope that makes sense.