property View.Key as Variant
Specifies the index or the caption of the column that determines the key of the view.

TypeDescription
Variant A long or string expression that specifies the index or the caption of the column that determines the key of the view.
The DataSource property can change the Key property using the Key field as explained bellow:

The Select property can select items using wild characters such as * or ?, if the view's SingleSel property is False.