Glossary for Geospatial Science

virtual field: A TNTmips database field that draws information from other database fields.� This information can be used directly or combined with the information from other fields or additional components.� There are two types of virtual fields: numeric, which are referred to as computed fields, or strings, which are called string expression fields.� An example of a computed field is population density, which may take population from one table, area from another, make the division and apply appropriate conversion factors for the desired output units.� A string expression field might concatenate the contents of separate fields, such as section, township, and range or create a multiline DataTip from a number of different fields, such as address, owner name, and property value for a parcels vector object.