  In this paper we introduce the notion of spread net. Spread nets are (safe)
Petri nets equipped with vector clocks on places and with ticking functions on
transitions, and are such that vector clocks are consistent with the ticking of
transitions. Such nets generalize previous families of nets like unfoldings,
merged processes and trellis processes, and can thus be used to represent runs
of a net in a true concurrency semantics through an operation called the
spreading of a net. By contrast with previous constructions, which may identify
conflicts, spread nets allow loops in time
