VPF is theNIMA standard format for vector data. Vector databases can be large, so VPF is hierarchically organized. A VPFproduct is distributed as a database . The database can be dividedinto several libraries , which can be defined by geographic extent,scale, or some other user-defined criteria. An example of a library is theNorth American continent.
Libraries have one or more coverages .
A coverage is a basic unit ofdata organization, and can be thought of as a separate layer of informationwithin a library. Boundaries, Rivers, and Transportation could all be examplesof coverages. Within a coverage there are feature classes . A feature class is agroup of related features . The Transportation coverage could be madeup of the Roads, Railroads, and Airports feature classes.