 BPMN, while intended to serve as a standard, is deficient in this regard, and so several commercial packages (such as Microsoft Biztalk) address these needs in proprietary ways (specifically, by enhancing the basic set of diagramming icons with additional icons that support the needed functionality).For the purpose of static analysis, e.g.to detect semantic errors at design-time, it is also possible to represent workflow in a mathematical form using a formal notation such as Petri nets.