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The SEDRIS Data Representation Model
APPENDIX A - Classes Property Set Index Control Link |
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An instance of this DRM class specifies an <Expression> instance that determines the index field value of all target <Property Set Index> instances, thus controlling which <Property Set> instance is referenced by each such <Property Set Index> instance.
Note that since each controlled <Property Set Index> instance may be bound to a different <Property Set Table Group> instance, and thus to a different primary <Property Set Table> instance, the fact that their index values are the same does not mean that the set of <Property Set Index> instances controlled by a given <Property Set Index Control Link> instance reference the same <Property Set> instance.
A tree canopy appears different at different times of the year, with a different colour and texture. This could be achieved by using a different <Property Set> for each period of the year. Each <Property Set> would contain the appropriate <Colour> and <Image Mapping Function>. A <Property Set Index Control Link> would be used to allow the appropriate <Property Set> to be selected.
A <Property Set Index Control Link> controls the value of the index stored in the <Property Set Index> instances that reference it.
No. The index always refers to the primary <Property Set>.
No. The link to the <Property Set Table Group> is an association within the transmittal, and associations cannot be changed dynamically.
| SE_String | description; | (notes) |
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| SE_Integer_Positive | expr_index; | (notes) |
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The description field specifies a text description of the given <Control Link> instance's purpose.
The expr_index field specifies the component <Expression>, the value of which controls the index of the affected <Property Set Index>.
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