Subroutines may be accessed from within a Workplace Shell object, in much the same manner as from any other program. Normal programming language calling conventions are used. Subroutines used by the object may reside within the same DLL as the object itself, or may be in a different DLL.
A number of guidelines for the use of subroutines within Presentation Manager applications are given in The Presentation Manager Application Model. Note that similar guidelines apply to the use of subroutines within Workplace Shell objects, since these objects should also adhere to object-oriented programming principles.