OK, so I looked up Tau on Dictionary.com and here's what it said (there was more but you had to subscribe or something):
TAU: An elementary particle of the lepton family, having a mass about 3,550 times that of the electron, a negative electric charge, and a mean lifetime of 3 × 10 to the (-13) seconds.
Taking that into account, AST is the First (or beginning) Sum of an elementary particle of the lepton family.
I love being a lepton. The negative charge is only for a short while!!
PsychTau