Architecting and designing : IDEF : IDEF3 : Modeling object state with IDEF3 : OSTN scenarios
  
OSTN scenarios
A scenario is a collection of all IDEF3 process and object state transmission models for a defined need, purpose, and scope.
A scenario can be thought of as one of the following items:
a particular recurring situation within an organization for which documentation is required
a set of situations which describes a typical class of problems addressed by an organization or system
the setting within which a process occurs
See also
Modeling object state with IDEF3