Visual dBASE 5.7, 16-bits DLL, optional parameters

Hi group,

I've written a 16-bits DLL (containing functions, using the C calling
convention) which I want to use in Visual dBASE 5.7.
Some of these functions are equipped with optional parameters.

Is it possible in VdB5.7 to pass parameters optionally?!
For example, something similar to this;

extern cdecl clogical myfunction (cstring, cstring, optional clong,
optional clong) mydll.dll
return myfunction (mystring1, mystring2 [, myvalue1, myvalue2])

Thanks in advance...