  The nominal transition systems (NTSs) of Parrow et al. describe the
operational semantics of nominal process calculi. We study NTSs in terms of the
nominal residual transition systems (NRTSs) that we introduce. We provide rule
formats for the specifications of NRTSs that ensure that the associated NRTS is
an NTS and apply them to the operational specification of the early
pi-calculus. Our study stems from the recent Nominal SOS of Cimini et al. and
from earlier works in nominal sets and nominal logic by Gabbay, Pitts and their
collaborators.
