  Tabular notations, in particular SCR specifications, have proved to be a
useful means for formally describing complex requirements. The SCR method
offers a powerful family of analysis tools, known as the SCR Toolset, but its
availability is restricted by the Naval Research Laboratory of the USA. This
toolset applies different kinds of analysis considering the whole set of
behaviours associated with a requirements specification. In this paper we
present a tool for describing and analyzing SCR requirements descriptions, that
complements the SCR Toolset in two aspects. First, its use is not limited by
any institution, and resorts to a standard model checking tool for analysis;
and second, it allows to concentrate the analysis to particular sets of
behaviours (subsets of the whole specifications), that correspond to particular
scenarios explicitly mentioned in the specification. We take an operational
notation that allows the engineer to describe behavioural "scenarios" by means
of programs, and provide a translation into Promela to perform the analysis via
Spin, an efficient off-the-shelf model checker freely available. In addition,
we apply the SCR method to a Pacemaker system and we use its tabular
specification as a running example of this article.
