In GUI mode, if setdef is set to three dots ("..."), then INFLD appears as combo box, but any action that would cause the drop-down box to appear (clicking on the drop down button or hitting Alt+Down) instead causes INFLD to exit with exitcode 29. The idea is to allow the application to then build its own list of choices based on the partial data entered in the field. See Self Service Combo Box.
See Also: