the function-behavior representation language FBRL was originally devised for modeling and knowledge management of intended product behavior. This paper explores its potential for application to other-than-intended behavior in a use context, introducing consideration of the user and the environment. We found that slightly adapted building blocks from as-is FBRL can be applied to behavior that is unintended and/or not performed by the product. To support anticipation of unintended behavior in design, special attention has to be paid to the knowledge that connects product functions, user actions and environment behavior. We distinguish typical and atypical forms of unintended use. Some forms of typical unintended use can be directly derived from the intended use. Yet, most forms of unintended use require additional knowledge, e.g., from user observations. To include such knowledge, subsequent effort has to be put into its systematization