No you just create the UDF and make the source the stock field. No need for a script.  

Ok found where to make source stock field... thanks much!!

BigLouie,

That is only true for different tables.  Same table: you need a script.

Once I added UDF it did show in select field list but when running report it didn't filter so I added the source field now need to update tonight then will try report again and we'll see... 

Yes, a UDF if the right table is added to the Selection grid... but data flow only works in certain circumstances, and never within a record.  So, you can copy a value into an SO UDF from a customer field, or into an invoice UDF from an order field, but not into an order UDF from a stock field in that same order.  (If you see a possible data flow for that, it is only effective for the "Copy From" feature, when creating a new SO from an existing order).

If you are needing the filter to work with existing records you will need to import to your UDF from the related field.

Hows is that done???

You can import from the same table to itself by using "File Type" "ODBC Data Source" and select "SOTAMAS90" unless you're using the Premium version in which case you would use a SQL Server DSN.