Term used in GIS technologies in the vector type of internal data organization: spatial data are divided into point, line and polygon types. In most cases, point entities (nodes) are specified directly as coordinate pairs, with lines (arcs or edges) represented as chains of points. Regions are similarly defined in terms of the lines which form their boundaries. Some vector GIS store information in the form of points, line segments and point pairs; others maintain closed lists of points defining polygon regions. Vector structures are especially suited to storing definitions of spatial objects for which sharp boundaries exist or can be imposed.