Class Name: Union Of Feature Topology

Superclass - <Feature Topology Hierarchy>

Subclasses

Definition

An instance of this DRM class is a collection of all of the <Feature Topology> instances that form a complete topological surface.

Primary Page in DRM Diagram:

• 11

Secondary Pages in DRM Diagram:

Example

1. A thematic layer representing a transportation network might be broken up into 4 rectangular tiles. While the <Linear Features> representing roads are allowed to extend across the tile boundaries, the <Feature Topology> instances that are located within each tile are organized into separate <Union Of Feature Topology> instances to support access by spatial location.

FAQs

What is the purpose of this class?

This class allows <Feature Topology> instances to be grouped in an arbitrary manner. It is used to ensure that all <Feature Topology> instances, particularly those that are not directly associated with any <Feature>, have at least one aggregate.

Constraints

• <<Perimeter Related Organizing Principle>>

Composed of (two-way)

• one or more <Feature Topology> instances

Component of (two-way)(inherited)

• one or more <Aggregate Feature> instances

Component of (two-way)

• zero or one <Perimeter Related Feature Topology> instance through <Perimeter Data>
• zero or one <Spatial Index Related Feature Topology> instance through <Spatial Index Data>

Inherited Field Elements