Some API methods return a comma-separated list of feature identifiers. The nature of a feature identifier depends on the type of layer to which the feature belongs. The are two categories:
Containing layer is either a CARIS File Layer, transient layer, or special layer
Containing layer is an ESRI Shape Layer
(See Overview of Data Layering.) For category 1, the identifier is a CARIS Key. For category 2, the identifier is the DBF value in the column identified in the SAF as the “primary key” column and the row corresponding to the feature. If the current selection has features belonging to both categories, then the returned list of identifiers will be a mixture of CARIS Keys and DBF values. If a feature has a missing identifier, then the corresponding position in the returned list has the designation "NO KEY". If there are no selected features, the returned string is empty, i.e. "".