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The SEDRIS Data Representation Model
APPENDIX A - Classes Axis |
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An instance of a concrete class derived from this DRM class specifies a set of values of an independent variable to be used to organize the dependent values in an instance of <Data Table>.
A table of Digital Terrain Elevation Data (DTED) contains terrain elevation data sampled in a grid of regularly spaced longitude and latitude points. The <Axis> components of such a table are longitude and latitude.
A table of ocean temperature and salinity data taken at varying depths by an expendable bathythermograph can be captured in a table. Such a table would have depth as an <Axis>, and temperature and pressure would be <Table Property Description> components. If these data were taken at intervals along a path, the locations on that path (say longitudes) would form a second <Axis> of the now two-dimensional table.
The values on a single <Axis> shall be distinct values of a single variable specified by the axis_type. If the axis is numeric, the values shall be arranged monotonically.
An <Axis> shall have at least one value; an axis with no values is a violation of SEDRIS' constraints. If the <Axis> has a single value, this implies that all of the data in the table shares that value. There may be better ways to associate a single value with all the table entries.
No. A data provider should include the meaningless cells, and set a value for EVC_NOT_APPLICABLE, and use it for those cells.
| EDCS_Attribute_Code | axis_type; | (notes) |
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| SE_Short_Integer_Positive | axis_value_count; | (notes) |
The axis_type field specifies the property being described by the given <Axis> instance.
The axis_value_count field specifies the number of "hash marks" along the given <Axis> instance.
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