The SEDRIS Data Representation Model
APPENDIX A - Classes
Table Property Description

Class Name: Table Property Description

Superclass - <SEDRIS Abstract Base>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class specifies a cell data element within a <Data Table> by providing

  1. an EAC, SE_Index_Code, or SE_Variable_Code, identifying the meaning of the cell data element,

  2. a value_type that specifies its storage type,

  3. an EUC and ESC that together specify the scaled unit of measurement.

The complete structure of a cell within the given <Data Table> is described by the complete ordered set of <Table Property Description> components of that <Data Table>.

Additional information about the cell property being described, where such information is to be applied throughout the scope of the <Data Table>, such as sentinel values and tolerances, is specified by attaching <Property Characteristic> components to the applicable <Table Property Description>(s).

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. 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_SALINITY, EAC_MEAN_WATER_BODY_TEMPERATURE, and EAC_WATER_BODY_SOUND_SPEED at that location.

    Table Property Description, Example 1

FAQs

Why is the value_type field needed?

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>'s own fields, but shall be specified at the <Table Property Description> level.

Unlike <Property Value>, which contains a complete EDCS_Attribute_Value, <Table Property Description> 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>, rather than any part of the <Table Property Description> itself.

What is the purpose of the component_data_table_ecc field and the optional <Property Value> components?

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 Tables>.

In these cases, the component_data_table_ecc, possibly elaborated by optional <Property Values>, is needed to distinguish index values in any given cell.

See <Classification Data> and the <<Index Codes within Tables>> constraint for further information.

Constraints

Composed of (two-way)

Component of (two-way)

Inherited Field Elements

This class has no inherited field elements.

Field Elements

SE_Element_Type meaning; (notes)
EDCS_Unit_Code value_unit; (notes)
EDCS_Scale_Code value_scale; (notes)
SE_Data_Table_Data_Value_Type value_type; (notes)
EDCS_Classification_Code component_data_table_ecc; (notes)

Notes

Composed of Notes


Property_Value

 These components are provided only when the given
 <Table Property Description> serves as an index into another
 <Data Table>, specifically, when the target <Data Table>'s
 <Classification Data> is elaborated by <Property Value> components.

 When such elaboration is present in the target, the
 <Property Value> components of this <Table Property Description>
 shall match those in the target.

Fields Notes


meaning

 The meaning field specifies the meaning of the given
 <Table Property Description> instance.

value_unit

 The value_unit field specifies the unit of measurement of the given
 <Table Property Description> instance.

value_scale

 The value_scale field specifies the scale applicable to value_unit.

value_type

 The value_type field specifies the storage type of the given
 <Table Property Description> instance.

component_data_table_ecc

 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 used only if the given <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_ELEM_CODE_TYP_INDEX,
                {SE_INDEX_CODE_DATA_TABLE_COMPONENT }}
 or
    meaning = { SE_ELEM_CODE_TYP_INDEX,
                {SE_INDEX_CODE_DATA_TABLE_LIBRARY }}

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Last updated: July 16, 2004 Copyright © 2004 SEDRIS