I get the 58" but what does the AMO stand for?  It's handwritten on my Hoyt Pro Hunter Re-curve.

 The May 2000 AMO (Archery Manufacturers & Merchants Organization – now under the leadership of the Archery Trade Association) Standards states "AMO Bow Length Standard is designated to be three inches longer than AMO Bow String Master that braces bow at proper String or Brace Height. Bow String Master will carry only the bow length designation. Example: A Bow String Master designated as AMO 66" (bow length) will have an actual length under tension of 63"."  That means your bowstring should be approximately 3 inches shorter than the bow's AMO length (the AMO length of your bow is 60 inches – IF it says AMO 60" [or 60" AMO] on the bow). If it actually is 60" AMO, just take the bow to a good archery store and ask for a 60-inch AMO string.
Hope this helps...

Archery Manufacturers Organization

I cut and pasted this from the AMO Standards literature for you.  It shows how they come up with the draw length.

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.