I've configured a combo box in the following way:

combo1.controlsource = table1.field1
combo1.rowsourcetype = 2
combo1.rowsource = list1.desc
combo1.style = 0

In runtime, selecting an item from its list will populate table1.field1 with that item. If, however, text is type into the control that does not appear in list1 it will not be written back to table1.field1. How can combo1 be setup so that selecting an item from its list or typing in a new value will populate its control source?