The SEDRIS Data Representation Model
APPENDIX A - Classes
Colour Table

Class Name: Colour Table

Superclass - <SEDRIS Abstract Base>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance T of this DRM class specifies an ordered collection of <Primitive Colour> instances such that, for the <Colour Table Group> instance G of which T is itself a component, the index field of any <Colour Index> instance associated to G unambiguously specifies one of the <Primitive Colour> components of T.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. Consider a data provider whose format specifies colours using palettes. To convey exactly the colour information used, each palette is represented as the primary <Colour Table> component of a <Colour Table Group> instance.

FAQs

Why do <Colour Table> instances have <Primitive Colour> rather than <Inline Colour> components?

A <Colour Table> instance does not contain <Inline Colour> components, because a <Colour Table> exists to store "just the colour", without any additional <Translucency>.

  1. The interpretation of a <Colour Index> is clearer if the referenced <Colour Table> entry cannot have additional <Translucency>.

  2. Storing <Primitive Colour> instances in a <Colour Table> allows greater re-use, since the same <Primitive Colour> can be referenced by different <Colour Index> instances with different <Translucency> components.

Constraints

Composed of (two-way)

Composed of (two-way metadata)

Component of (two-way)

Inherited Field Elements

This class has no inherited field elements.
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Last updated: July 26, 2006 Copyright © 2006 SEDRIS