TIGER/LINE(TM) Files, 1992
Appendix B
SDTS Definitions for Spatial Objects
The spatial objects in TIGER/Line belong to the "Geometry
and Topology" (GT) class of objects in SDTS. The
definitions are from FIPS Publication 173, SPATIAL DATA
TRANSFER STANDARD (SDTS) (August 28, 1992) Section 2-2,
Classification and Intended Use of Objects, pp. 11-20.
* Node: "A zero-dimensional object that is a
topological junction of two or more links or chains, or
an end point of a link or chain," is a node.
* Entity point: "A point used for identifying the
location of point features (or areal features collapsed
to a point), such as towers, buoys, buildings, places,
etc."
* Complete chain: "A chain [a sequence of non-
intersecting line segments] that explicitly references
left and right polygons and start and end nodes." The
shape points combine with the nodes to form the segments
that make a complete chain.
* Network chains: "A chain that explicitly references
start and end nodes and not left and right polygons."
* GT-polygon: "An area that is an atomic two-
dimensional component of a two-dimensional manifold,
[which is defined as] one and only one planar graph and
its two-dimensional objects." GT-polygons are
elementary polygons that are mutually exclusive and
completely exhaust the surface.