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The background to this question is in Understanding difference between Coordinate System and Projection?
There @mdsumner commented:
WGS84 is not a cs, it's a datum.
On a couple of places online I have found: "WGS84 geographic coordinate system" mentioned. Is this an incorrect terminology?
WGS84" is a datum, but "WGS84" is also a geographic coordinate system defined by the "WGS84" datum?
Both. It's also a geographic coordinate reference system and an ellipsoid, and sometimes a spheroid, and a bunch of other related/similar terms that are used in the fields of geodesy, geomatics, geography, etc.
The US military started the process by using the same name "World Geodetic System 84" for an earth gravitational model, an ellipsoid, and a geodetic datum.
Since then, terminology has moved on, with ISO and OGC using coordinate reference system that contains a datum plus a "coordinate system." For them, a coordinate system is the axes order and direction plus names and abbrevations and the unit.
I think it's sloppy terminology to use it as a cs, it is not technically one just because it's used that way. If I hear 'GDA94', I have to ask what UTM zone is implied, or if the datum is really what was meant. The sloppiness is reflected in interchange formats where it is implied rather than recorded explicitly. Practitioners can guess solutions, but beginners are understandably confused.
It's a vicious cycle.
