8Tn refers to the nth transitive subgroup of S8 in the GAP classification scheme.
16Tn refers to the nth transitive subgroup of S16 in the GAP classification scheme.
Technical Note: Systems of injections (charge models with only 8 functions) are best viewed as orbit models. Any compatible index-2 subgroup H acts transitively on a single orbit of size 8 (hence an 8Tk label applies). The full charge construction F×{A,B} is an intransitive H-set with two orbits; it is not itself an nTk object unless extended by a sheet-swapping element, yielding a transitive 16Tl action.