What is the difference between elongation A and AGT?

The breaking elongation A is the ductility index of the reinforcement, but it is only the resident elongation of broken region rather than the ductility of the reinforcement.Total elongation rate of maximum load Agt denotes the elongation up to ultimate load without reduction of cross­ section.

Usually elongation, A, has double the value of Agt.

The ductility of Agt > 5% is required for the finished hollow-bar,

not for the steel tube it is manufactured from and which is given on the mill      certificate of the steel mill.
(By Titan I ASTM A370)

What's the difference between water glass and silica sol process?

How to measure AGT?