Assign Set in constrant

I have a set
set S
p1 / 1 ,2, 3 /
p2 / 4,5 /
p3 /6, 7 /
p4 / 8 /
p5 / 9 /
p6 / 10, 11, 12, 13 ,14, 15/;

I want to impliment the same with the following mathematical eq.
forall (i in P)
sum(j in S(i)) Z(j) <= 10^100;

Hi
Your example is not clear to me. Either post your GAMS code or make your example more explicit, so people can try to find an answer for you.
Cheers
Renger