>Hi,
>
>I have a function that receives a parameter, an array. The code is as follows:
>
>

>Function MyFunc
>LPARAMETERS tParam1, tParam2, taMyArray
>EXTERNAL ARRAY taMyArray
>

>
>I need to add the 4th parameter. In the case of the 4th parameter the 3rd is not necessary. If I pass the 3rd parameter (taMyArray) set to NULL will I have a problem? Since the next line (EXTERNAL ARRAY taMyArray) expects this parameter to be an array.

You could as well pass something else as 3rd parameter and then instead of checking whether it's null, check whether it's an array or not.