Some of the terms requiring explanation are below. A system of grid cells of uniform size within one data set. A representation based on vector coordinates of graphic features. A data set does not retain spatial relationships between spatial features. The points, arcs and polygons are isolated featufes.
Spatial relationships exist between selected significant points and arcs only.
For example, end and intersections points of arcs are designed as significant points of arcs. This observes first a degree one topology and retains explicit relationships between arcs and polygonal regions, for example, an arc retains the knowledge of which polygons are to the left and to the right of the arc. This observes first a degree two topology and further retains relationships between surfaces and volumetric features. This refers to demonstrations and tutorials in person, or film, video. 22.0 Provider of Directory Information .