All choices have a selection. This is a state representing the items currently selected. The selection is represented as a vector of offsets into the list of the choice's items, unless it is a single-selection choice, in which case it is just represented as an offset.
The initial selection is controlled with the initarg
. The accessor
Generally, it is easier to refer to the selection in terms of the items selected, rather than by offsets, so the CAPI provides the notion of a selected item and the selected items . The first of these is the selected item in a single-selection choice. The second is a list of the selected items in any choice.
and the initargs
provide access to these conceptual slots.