Battery specification

What is the standard GTA battery specification? What do the various descriptions on batteries mean AH, cranking amps etc?

AH is for Amp Hours, eg 90Ah.
I think the theory is that the battery can supply 90 Amps for 1 hour or 180 Amps for half hour or 30 Amps for 3 hours etc.. Sounds a lot of current for a long time though.
Cranking draws a lot more current as well.

Ah is how many amps a battery can supply over 20 hours down to about 10 volts, so a 90ah battery can supply about 4.5 amps per hour until it is dead.

And GTA spec batteries are????

Page 58 of the drivers hand book says:
"12v 250A /50Ah"