The data structure itself can be thought of as a template or skeleton within which the geospatial features and metadata are stored. Basic VPF Structure VPF has three basic data structures. All VPF data is defined in terms of one of these structures. There are several hierarchical directories in VPF which are described below. Feature, attribution, location, geometry, and topology information is stored in various VPF tables.
Indices are a special kind of table which have pointers between other tables and records.
To facilitate faster access to primitive data, most VPF products are tiled. That is, the extent of the library is broken into tiles of equal size. Topology among VPF features is only maintained within each coverage. Therefore VPF does not store topology between features which are in different coverages. A glossary of VPF related terms is available in the VPF Glossary VPF Products Just as there are several different types and scales of charts and maps that may be created for the same geographic area, each designed for different uses, there are also several types of VPF products of different levels of feature content and density.