Release 10.1A: OpenEdge Development:
ADM Reference

enterCombo

This procedure fires a trigger on entry into a Combo field to store the current screen value of the displayed field.

Location: combo.p

Parameters: None

Notes: The typical case is that the displayed field are not the same as the keyfield. In that case, logic can be fired when the displayed field is changed in the leave trigger to see if the new value keyed in actually exists as a unique record, and if so, avoid having to use the combo.