[Esip-documentation] proposed new wording for geospatial bounds attributes

[John Graybeal via Esip-documentation]

Per the recent exchanges, I'd like to propose the following wordings for geospatial bounds attributes. 

I think that EITHER (a) this wording addresses all the issues raised to date, and is likely to be largely acceptable, OR (b) there will remain some fundamental disagreement, in which case we needn't consider this one further. But I wanted to get it on the table, as I think it represents a workable conclusion to the issues/discussion to date.

geospatial_bounds: 

Describes the data's 2D or 3D geospatial extent in OGC's Well-Known Text (WKT) Geometry format (reference the OGC Simple Feature Access (SFA) specification). The meaning and order of values for each coordinate point depends on the coordinate reference system (CRS). In ACDD the default CRS is EPSG:4326 for 2-dimensional geometries, and EPSG:4979 for 3-dimensional geometries; the default may be overridden using geospatial_bounds_crs and/or geospatial_bounds_vertical_crs (see those attributes). The values may be approximate. Example: EPSG:4326 coordinate values are latitude (decimal degrees_north) and longitude (decimal degrees_east), in that order, thus: "POLYGON ((40.26 -111.29, 41.26 -111.29, 41.26 -110.29, 40.26 -110.29, 40.26 -111.29))". (Note that neither default CRS restricts longitude values to the [-180, 180] range.)

geospatial_bounds_crs:

The coordinate reference system (CRS) used by the coordinates in the geospatial_bounds attribute.  This CRS may be 2-dimensional or 3-dimensional, but (together with geospatial_bounds_vertical_crs, if that attribute is supplied) must match the dimensionality, order, and meaning of point values in the geospatial_bounds attribute. EPSG CRS's are strongly recommended.. If this attribute is not specified, the CRS is assumed to be EPSG:4326 for 2-dimensional geometries, and EPSG-4979 for 3-dimensional geometries. Examples: "EPSG:4326" (the 2D WGS84 CRS) and "EPSG:4979" (the 3D WGS84 CRS).

geospatial_bounds_vertical_crs:

The vertical coordinate reference system used by the Z coordinates in the geospatial_bounds attribute; may not be used if the CRS in geospatial_bounds_crs is a 2-dimensional CRS. EPSG CRSs are strongly recommended.  The default if unspecified is the vertical component of EPSG:4979 (height above the ellipsoid, in meters). Examples: "EPSG:5829"  (instantaneous height above sea level), "EPSG:5831" (instantaneous depth below sea level), or "EPSG:5703" (NAVD88 height).


John



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