taIVTransferHeaderInsert Class - USRDEFND1 property error

Hi,

 Does anyone one know which table does the E-connect class - taIVTransferHeaderInsert inserts to?

How do I change the data type of USRDEFND1 property since I'm getting the error below when passing a value to this property.

 (Microsoft.Dynamics.GP.eConnect.eConnectException) Error converting data type char to smallint.

msdn.microsoft.com/.../ff623396.aspx