Abstract: A method and apparatus for defining a system design specification by using a finite set of templates that have a format for accepting a set of system expression such that a selected template, when filled with the system expressions, defines an intended behavioral attribute of the system. In one illustrative embodiment, each template has a set of qualifiers and a set of entry blanks, wherein each qualifier is associated with an entry blank. In such an embodiment, the set of entry spaces may comprise a fulfilling condition entry space for accepting a system expression that defines a required or assumed event of the system model, an enabling condition entry space for accepting a system expression that defines a precondition for starting a check of the required or assumed event, and a discharging condition entry space for accepting a system expression that defines a condition after which said fulfilling condition is no longer required or assumed by the system model.