Interactive Sketching Notation

Jakub Linowski created a sketch annotation system for interaction design and provides a free downloadable PDF describing how to use it.

"The interactive sketching notation is an emerging visual language which affords the representation of interface states and event-based user actions. Through a few simple and standardized rules, what the user sees (drawn in greys and blacks) and does (drawn in red) are unified into a coherent sketching system. This unification of both interface and use, intends to enable designers to tell more powerful stories of interaction. "