Technically there is ISCG RevA, ISCG RevB (a.k.a. ISCG-OLD, a.k.a. ISCG-03, a.k.a. ISCG) and ISCG-05.
ISCG-05 was a larger collab project between various component and frame makers that took a lot more things into account. For instance, the tab rotation is dictated by the location of the...