The document discusses programming in UML using the Foundational UML (fUML) standard and the Action Language for fUML (Alf). It provides an overview of fUML and Alf, which define an executable subset of UML and a textual action language for specifying behaviors in UML models. The document uses a motivating example of an e-commerce ordering system to illustrate key concepts of executable UML including activities, actions, structure, and asynchronous communication.