  The present paper defines ST-structures (and an extension of these, called
STC-structures). The main purpose is to provide concrete relationships between
highly expressive concurrency models coming from two different schools of
thought: the higher dimensional automata, a \textit{state-based} approach of
Pratt and van Glabbeek; and the configuration structures and (in)pure event
structures, an \textit{event-based} approach of van Glabbeek and Plotkin. In
this respect we make comparative studies of the expressive power of
ST-structures relative to the above models. Moreover, standard notions from
other concurrency models are defined for ST(C)-structures, like steps and
paths, bisimilarities, and action refinement, and related results are given.
These investigations of ST(C)-structures are intended to provide a better
understanding of the \textit{state-event duality} described by Pratt, and also
of the (a)cyclic structures of higher dimensional automata.
