Ordered list of labels for all the axes of this CRS. The gml:axisAbbrev value should be used for these axis 
labels, after spaces and forbiddden characters are removed. When the srsName attribute is included, this attribute is optional. 
When the srsName attribute is omitted, this attribute shall also be omitted.

This attribute is included for backward compatibility with GML 2 and is deprecated with GML 3. 
This identifer is superceded by "gml:id" inherited from AbstractGMLType. The attribute "gid" should not be used 
anymore and may be deleted in future versions of GML without further notice.

Database handle for the object.  It is of XML type ID, so is constrained to be unique in the XML document within which it occurs.  An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.  This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.

If the orientation is "+", then the OrientableSurface is identical to the baseSurface. If the orientation is "-", then the OrientableSurface is a reference to a Surface with an up-normal that reverses the direction for this OrientableSurface, the sense of "the top of the surface". "+" is the default value.

The "srsDimension" is the length of coordinate sequence (the number of entries in the list). This dimension is 
specified by the coordinate reference system. When the srsName attribute is omitted, this attribute shall be omitted.

In general this reference points to a CRS instance of gml:CoordinateReferenceSystemType 
(see coordinateReferenceSystems.xsd). For well known references it is not required that the CRS description exists at the 
location the URI points to. If no srsName attribute is given, the CRS must be specified as part of the larger context this 
geometry element is part of, e.g. a geometric element like point, curve, etc. It is expected that this attribute will be specified 
at the direct position level only in rare cases.

Ordered list of unit of measure (uom) labels for all the axes of this CRS. The value of the string in the 
gml:catalogSymbol should be used for this uom labels, after spaces and forbiddden characters are removed. When the 
axisLabels attribute is included, this attribute shall also be included. When the axisLabels attribute is omitted, this attribute 
shall also be omitted.