AbstractThis paper describes the definition and the use of a plan language in the context of mathematical web services. A plan is a document intended to describe how to use different mathematical web services to solve a particular problem. A plan is like a program in which most of the function calls have to be handled by web services. A plan is a multiple-state choreography document which could be either abstract, unresolved or resolved, depending on how much of the web services involved in the choreography is known. Such a plan can be instantiated into a composition language such as BPEL or to a mathematical routine (like a Maple routine) for execution.