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The SEDRIS Data Representation Model
APPENDIX A - Classes Feature ID Control Link |
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The specialized <Control Link> used to provide the connection between an ordered aggregation of <Expressions> and the target fields of a <Feature_ID>.
The expr_index field is a 1-based index into the ordered aggregation of <Expressions>, and is used to select the specific <Expression> that controls the value of <Feature ID>'s ID field.
Consider a <Feature Model> containing a <Feature Node>, which has a <Feature ID> component. In this case, the data provider wishes to ensure that each <Feature Model Instance> uses a unique <Feature ID> for this node.
In order to do this, the data provider attaches a <Feature ID Control Link> to the <Feature ID> instance, where the ID field's controlling <Expression> is a <Variable>. In this way, each <Feature Model Instance> provides a different ID for the <Feature Node> within the <Model>.
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| SE_String | description; | (notes) |
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| SE_Integer_Positive | expr_index; | (notes) |
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This is a text description of the given <Control Link> instance's purpose.
This specifies which component <Expression> controls the ID of the affected <Feature ID> instances.
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