The name of the field that will be sent to the "On Expand" or "On Select" Webroutine containing the ID of the expanded or selected item. If not specified, the field specified by list_id_field will be used.
Blank. Use the value specified in list_id_field.
The name of a valid input field. A selection can be made from a list of valid fields by clicking on the corresponding dropdown button in the property sheet.