Petri-Box Calculus was conceived, among others, as a semantic domain
for high level parallel programming languages. In particular, within
the same project, such a language, called *B*(*PN*)^{2}, has been
developed [BH93].

*B*(*PN*)^{2} is a parallel programming language whose semantics has been
entirely expressed (and even implemented) in terms of Petri Box
Calculus. The using of basic Petri nets by the PBC had been the cause
of the problems of size explosion of the nets obtained as a semantics
of *B*(*PN*)^{2} program. A natural way to solve this problem was to
express the *B*(*PN*)^{2} semantics by means of a class of high level
Petri nets (colored nets), in particular to obtain a compact data
representation.

This was the motivation of the work on a high level nets model,
which began during the CALIBAN workshop in 1994 in Newcastle
(England). A first proposition of such a model was published in
[BFF^{+}95a] and an application of the model to the *B*(*PN*)^{2}
semantics in [BFF^{+}95b].

A revised and improved version of this work has been submitted and
recently accepted for publication in the journal *Acta
Informatica* [BFH^{+}97].