index map meaning in Information Science terminology / glossary / dictionary is:
An outline map showing the complete extent of the geographic coverage and the numbering system of a set or series of more detailed sheet maps, with or without segmentation. Click here to see an index map of road maps of King County, Washington (King County GIS Center) and here to see an index map of early topographicsheets of the San Juan Islands (Washington State University). Compare with map index. See also: key map.