How to Selectively Ship only few lines and not all in a Sales Order?

Hello,
How do I ship only some lines in a Sales order and not all using API? I am able to do this using STF(Shipping Trax Form).Below is the snippet I have written but it always ends up shipping entire order. What am I missing? Please advise.

This is on 11i 11.5.10.2

changed_attributes (1).delivery_detail_id := 1234
changed_attributes (1).shipped_quantity := 0
changed_attributes (x).source_line_id := 12344
changed_attributes (2).delivery_detail_id := 1235
changed_attributes (2).shipped_quantity := 66
changed_attributes (2).source_line_id := 12346
 changed_attributes (x).attribute4 := p_freight;
         changed_attributes (x).attribute5 := p_accessory;
         changed_attributes (x).attribute6 := p_othercost;
         changed_attributes (x).tracking_number := p_waybill;
--Call to WSH_DELIVERY_DETAILS_PUB.Update_Shipping_Attributes.
         wsh_delivery_details_pub.update_shipping_attributes