Most information handled by government is land and parcel related, so the parcel data is important in an urban or county information system. The parcel layer relies heavily on the base map and on the measurement data in legal descriptions. Once in operation, other transactions relate to the property layer itself, rather than its precursor layers. Building applications, land transfers, emergency response, as well as assessment functions, all rely on this layer.
Every parcel needs to be assigned a unique identification number.
The system for assigning this number should be legally defined and recognized by official entities as the primary reference for the individual parcel to all data and documents. This connection between secondary and primary identifiers allows for multiple uses of the data. It is ideal for the parcel numbering system to be economically implemented, structured for cost-effective maintenance and accessible for all users. A location identifier denotes the location of the parcel such as is used in map-based, geographic coordinate, and rectangular survey identifier systems. In the map-based system, the map, block and parcel numbers of the assessment maps are incorporated into the parcel identifier.