Note: Not all widgets might support the full syntax as described in here. For those you can only provide a PV name
Most widgets can react to ProcessVariables (PVs): They usually display the current value of the PV as a text, number or e.g. as a meter. Even seemingly static elements like lines can change their color based on the value of a PV.


EDM has the option of supporting several types of PVs. When simply providing a PV name, the default type of PV is used (usually EPICS). Otherwise, the type of PV is selected via a prefix:
     CALC\name(argA, argB, argC, ...)


If you want to implement a new widget, please refer to the header file edm/lib/pv_factory.h.