[aprssig] Definitive digipeater specification?

[scott at opentrac.org]

Is there any 'official' explanation of exactly how a modern APRS digipeater is supposed to function?  The AX.25 spec just covers the conventional digipeating.  I think I have a pretty good handle on it, but I know there's been some inconsistency out there.  Just want to make sure I'm working from the best source material available.

A flow chart or state diagram would be great...

Scott
N1VG