Index map

Not to be confused with Index mapping, an array technique in computer science.

An index map is a finding aid for a set of maps covering regions of interest along with a name or number of the relevant map sheet. It provides geospatial data on either a sheet of paper or a computer display, like a gazetteer, with the location (such as a call number) represented within a grid overlaying the map's surface.

An index map of South and Central America

Geospatial data is often preferred to political borders, which often change. Information is searchable by coordinates, rather than the metadata for a particular country and region that can be entered into a catalog. In various institutions, maps are cataloged individually or as sets, resulting in various levels of specificity.