DLPP--makes the most sense to me--but here's the wording--
AMO DRAW LENGTH STANDARD
For Manufacturers
Draw length is a specified distance, or the distance at the archer’s full draw, from
the nocking point on the string to the pivot point of the bow grip (or the theoretical
vertical projection of a tangency line to the pivot point parallel to the string)
plus 1 3/4”. Draw length from pivot point shall be designed at DLPP and shall be
called TRUE DRAW LENGTH.
EXAMPLE: 26 1/4” DLPP plus 1 3/4” is the equivalent of 28” draw.
For Dealers and General Use
For practical reasons not requiring precise terms, draw length is the distance, at
the archer’s full draw, from the nocking point on the string to the back of the bow
at the arrow rest.
EXPLANATION: The standard Manufacturers is consistent with the Bow
Weight Standard as related to the pivot point. The DLPP plus 1 3/4” is compatible
to previous concepts of draw length. (See handle illustration.) Draw length
for Dealers and General Use relieves the burden of preciseness not required for
general use and facilitates determining arrow length. THIS STANDARD SUPERSEDES
THE PREVIOUS STANDARD.
I also found this---
AMO CONVENTIONAL
BOW WEIGHT MARKING STANDARD
In accordance with the AMO Bow Weight Standard, the manufacturer has the
option to mark his bow with actual draw weight at 28” (26 1/4” DLPP) draw or to
use the following bow weight markings, especially on hunting models and middle,
and low end bows.
Example: Bows weighing 19 - 20 -21 lb. - will be marked 20 lbs.
Bows weighing 22 - 23 lbs. - will be marked 20X lbs.
Bows weighing 24 - 25- 26 lbs. - will be marked 25 lbs.
Bows weighing 27 - 28 lbs. - will be marked 25X lbs.
Bows weighing 29 - 30 - 31 lbs. - will be marked 30 lbs.
All other conventional bow weights not shown would follow this same formula.