For most operations
that involve the spatial database, you refer to composites of the
spatial data variables rather than directly to the variables in the
spatial data sets. A composite consists of the following elements:
-
a variable
association that identifies which variable or variables in the spatial
database comprise the association. The variable association can specify
a single variable, a pair of variables that define a bilateral (left-right)
association, or two pairs of variables that define the start and end
of a directional (from-to) bilateral association.
-
a class attribute that identifies
the role of the composite in the spatial database.
For example, if the
chains data set has a variable that is named FEANAME that contains
feature names, then you can create a composite for the FEANAME variable
that assigns the class attribute NAME to indicate that the composite
represents feature names. If the chains data set has COUNTYL and COUNTYR
variables that contain the codes for the counties on the left and
right sides of the chains, then you can create a composite that is
named COUNTY. The composite identifies the bilateral relationship
between these two variables and assigns the class attribute AREA to
indicate that the composite defines county areas in the spatial data.
Composites are created and modified using the COMPOSITE
statement in the GIS procedure. Composite definitions are stored in
the spatial entry.
See COMPOSITE Statement for more information
about using the GIS procedure to create or modify composites.