HOWTO: Use Optional Arguments in Intrinsic Data Types

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1. The Optional argument must be capable of being assigned a default value. When a procedure that has Optional arguments is called, Microsoft Visual Basic 5.0 assigns all arguments that were not included with a default value. Therefore, an Optional array is not possible.
2. Optional arguments of user-defined data types are not supported. Microsoft Visual Basic 5.0 only supports Optional arguments of intrinsic data types.
3. Optional arguments that are of intrinsic data types always return False when used with the IsMissing function. This occurs because the IsMissing

      function is explicitly designed for un-initialized Variant data types.
      Because an intrinsic Optional argument always gets its default value if
      not passed to the procedure, it is never missing.
   						

4. Applications written with earlier versions of Visual Basic for Applications will ignore the Optional modifier, and therefore require the argument(s). A good example of this is Microsoft Access for Windows 95.