  We introduce a renormalized 1PI vertex part scalar field theory setting in
momentum space to computing the critical exponents $\nu$ and $\eta$, at least
at two-loop order, for a layered parallel plate geometry separated by a
distance L, with periodic as well as antiperiodic boundary conditions on the
plates. We utilize massive and massless fields in order to extract the
exponents in independent ultraviolet and infrared scaling analysis,
respectively, which are required in a complete description of the scaling
regions for finite size systems. We prove that fixed points and other critical
amounts either in the ultraviolet or in the infrared regime dependent on the
plates boundary condition are a general feature of normalization conditions. We
introduce a new description of typical crossover regimes occurring in finite
size systems. Avoiding these crossovers, the three regions of finite size
scaling present for each of these boundary conditions are shown to be
indistinguishable in the results of the exponents in periodic and antiperiodic
conditions, which coincide with those from the (bulk) infinite system.
