Nulling Siebel Fields

Does anyone know how to null out Siebel fields? What I’m trying to do is update an address through the “Address” component, but the new address has only one line where the old one had 2. What would I have to pass in the input record to set the second address line to null? I’ve tried sending (null, $null, “”, etc) but it just puts the value I send into the database field. I’m currently using the Siebel Adapter v1 with Integration Server 4.6.