gRing is declared as GRingPointType
There was a short email exchange on the LTER best-practices mailing list about some confusion in the coverage schema, in the declaration for datasetGPolygonOuterRing. Peter and Wade may remember it.
Basically, you have this:
<xs:element name="gRingPoint" type="GRingPointType" minOccurs="3" maxOccurs="unbounded"/>
<xs:element name="gRing" type="GRingPointType"/>
The sequence of 3 or more <gRingPoint>s (lat-lon pairs) creates a ring, but the odd thing is that the other choice, <gRing> is also declared as a gRingPointType. There is a named type GRingType (a list of ordered pairs) which appears not to have been used, so it seems that gRing should have been declared a gRingType instead. Wade suggested this, but it never made it into this database.
If you all agree that this is indeed the case, I'll make the change and squeeze it into EML2.1.0rc3. It's is better located in 2.1.0, since it wont be backward compatible when it is fixed. Sorry for the timing - I ran into it today while diving back into an SBC project.