Pointer to a list model event.
Event code that identifies the type of event.
Indicates a relative position within the list whose value depends on the type
of change being communicated by the event. In general, this is the index of
the item effected by the change. For example, when an new item is inserted into
the list, this field identifies the index where the new item was added. Similarly,
when an item is deleted, this field identifies the index where the deleted item
Indicates the number of items stored in the list prior to a change to the list.
Indicates the number of items stored in the list after the change.