The SEDRIS Data Representation Model
APPENDIX B - Constraints
Property Meaning Restrictions

Definition

For a <Property> instance P (that is, an instance of one of the concrete subclasses of <Property>), the following conditions shall hold.

  1. If P is an instance of <Property Value>, its value. attribute_value_type shall be consistent with the restrictions imposed by the meaning of P.

  2. If P is an instance of <Table Property Description>, its value_type and those of the corresponding elements of any applicable <Data Table> instances shall be consistent with the restrictions imposed by the meaning of P.

  3. If P specifies a real-valued EA or real-valued SE_Variable_Code M as its meaning, the value_unit of P shall specify a unit belonging to the EDCS Unit Equivalence Class to which M is bound.

  4. If P does not specify a real-valued EA or real-valued SE_Variable_Code as its meaning, the value_unit and value_scale of P shall be set to EUC_UNITLESS and ESC_UNI, respectively.

Rationale

The data type and unit of measure shall be semantically valid for the meaning of the <Property>.

Example

  1. Consider a <Property Value> instance P specifying a numeric meaning, (in this example, EAC_WIDTH). To be semantically valid, the attribute_value_type of P's value shall be compatible with the abstract value type bound to EAC_WIDTH (REAL), and the value shall be a member of EQC_LENGTH.

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Last updated: July 16, 2004 Copyright © 2004 SEDRIS