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The SEDRIS Data Representation Model
APPENDIX A - Classes Table Property Description |
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An instance of this DRM class specifies a single data element for a cell within a <Data Table> instance by providing:
The complete structure of a cell within the given <Data Table> instance is described by the complete ordered set of <Table Property Description> components of that <Data Table> instance.
Additional information about the cell property being described, where such information is to be applied throughout the scope of the <Data Table> instance, such as sentinel values and tolerances, is specified by attaching <Property Characteristic> components to the applicable <Table Property Description> instance(s).
Consider a <Property Grid> instance containing sound speed data for a body of water. For each spatial location in the grid, the corresponding cell in the <Property Grid> instance specifies the properties of EAC_PRACTICAL_SALINITY, EAC_MEAN_WATERBODY_TEMPERATURE, and EAC_WATERBODY_SOUND_SPEED at that location as depicted in Figure 70:
The storage type of each cell data element shall be specified, and each cell data element shall be allowed to specify its own storage type. This means that the storage type information cannot be stored in the <Data Table> instance's own fields, but shall be specified at the <Table Property Description> instance level.
Unlike a <Property Value> instance, which contains a complete EDCS_Attribute_Value, a <Table Property Description> instance only needs to to specify the storage type without a value being stored, since the values being described are the cells of the <Data Table> instance, rather than any part of the <Table Property Description> instance itself.
Consider a <Data Table> instance with more than one <Table Property Description> supplying the same SE_Index_Code as a meaning, where that meaning is that each such <Table Property Description> acts as a signature element to reference other <Data Table> instances.
In these cases, the component_data_table_ecc, possibly elaborated by optional <Property Value> components, is needed to distinguish index values in any given cell.
See <Classification Data> and <<Index Codes within Tables>> for further information.
When the meaning field value specifies an EAC, the <Property Value> components qualify the meaning field value.
When the <Table Property Description> instance serves as an index into another <Data Table> instance, <Property Value> components are present when the <Classification Data> component of the target <Data Table> instance is elaborated by <Property Value> components. When such elaboration is present in the target, the <Property Value> components of this <Table Property Description> instance shall match those in the target.
The meaning field specifies the meaning of the <Table Property Description> instance.
The value_unit field specifies the unit of measurement of the <Table Property Description> instance.
The value_scale field specifies the scale applicable to value_unit.
The value_type field specifies the storage type of the <Table Property Description> instance.
The component_data_table_ecc field specifies the ECC used to identify the table type of a component or library <Data Table> instance. It is only used if the <Table Property Description> instance is describing an index that refers to a <Data Table> instance. This, in turn, is only the case if meaning = {SE_ELEMTYPCOD_INDEX, {SE_IDXCODE_DATA_TABLE_COMPONENT}} or meaning = {SE_ELEMTYPCOD_INDEX, {SE_IDXCODE_DATA_TABLE_LIBRARY}}
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