Scenario

A scenario (from the Italian, that which is pinned to the scenery) is a brief description of an event or a series of events. In the Commedia dell'arte it was an outline of entrances, exits, and action describing the plot of a play that was literally pinned to the back of the scenery. It is also known as canovaccio or "that which is pinned to the canvas" of which the scenery was constructed.
In the creation of an opera or ballet, a scenario is often developed initially to indicate how the original source, if any, is to be adapted and to summarize the aspects of character, staging, plot, etc. that can be expanded later in a fully developed libretto, or script. This sketch can be helpful in "pitching" the idea to a prospective producer, director, or composer.