Class Name: Property Table Reference

Superclass - <SEDRIS Abstract Base>

Subclasses

Definition

An instance of this DRM class specifies a reference to an N-1 dimensional "slice" of an N-dimensional <Property Table> component of a <Data Table Library>, where N is the number of <Axis> components of the <Property Table>.

<Property Table Reference> exists primarily to allow a data provider to select a set of parameters from a standard <Property Table> containing an indexed collection of alternatives.

Since only one <Axis> requires a specific "tick mark" to be specified, <Property Table Reference> specifies the axis_type of the <Axis> to be matched, and the index_on_axis specifies the "tick mark" on that <Axis>.

Primary Page in DRM Diagram:

• 18

Secondary Pages in DRM Diagram:

• 3
• 6
• 8
• 16
• 19
• 22

Example

1. See <Property Table Reference Control Link>, example 1.

FAQs

Why not use a collection of <Property Value> instances instead of a <Property Table Reference> instance?

In some cases this might be possible, and is not prohibited. However, some tables are multi-dimensional. It would not be possible to define <Property Value> instances to designate each combination of axis values that occur in a multi-dimensional table.

Why an N-1 dimensional slice?

This is the only case for which there is a currently identified need, given the recursive composition capabilities of the <Property Table> class.

What restrictions are there on axis_type?

The referenced <Property Table> shall contain an <Axis> with a matching axis_type; otherwise, there are no restrictions. Any <Axis> within the target <Property Table> may be specified.

Why is index_on_axis a zero-based index?

Because the corresponding <Axis> data structures for "tick marks" are C arrays, and C uses zero-based indices for arrays.

Constraints

• <<Publishable Object>>
• <<Non Crossing Associations>>
• <<Reference To Data Table Library>>

Associated to (one-way)

• one <Property Table> instance

Composed of (two-way)

• zero or one <Property Table Reference Control Link> instance

Component of (two-way)

• zero or more <Feature Representation> instances
• zero or more <Geometry Representation> instances
• zero or more <Image> instances
• zero or more <Predefined Function> instances
• zero or more <Property Set> instances
• zero or more <Property Table> instances
• zero or more <Vertex> instances

Inherited Field Elements

Field Elements

Notes

Fields Notes

axis_type

 The axis_type field specifies the property being described by
 the target <Axis>.

index_on_axis

 The index_on_axis field specifies the (0-based) index of the
 "tick mark" being referenced on the specified <Axis>. This
 allows the "tick mark" to be specified in a manner independent
 of the class of the <Axis>. The only restriction is that the
 value of index_on_axis shall be between zero and
 axis_value_count-1 for the specified <Axis>.

 If index_on_axis specifies some value j, then the (j+1)th
 "tick mark" on the <Axis> is being referenced, regardless
 of the data type of the tick marks specified by the specific
 subclass of <Axis> being used.