Gpa vs asgpa

ASGPA work like same GPA or any else?? My brother taken Agreement of sale cum GPA from owner of 500 square yards in 2009, now principal are alive or not don't know, my brother has sale agreement and possession from long back, my bother can get title? need register sale deed for title?? if its only GPA principal not alive its not valid, but it is ASGPA , can claim title if principal not live?