for efficiency reasons, GML also provides a means of encoding the range set in
an arbitrary external encoding, such as a binary file. This encoding may be "well-known" but
this is not required. This mode uses the gml:File element. The values of the coverage
(attribute values in the range set) are transmitted in a external file that is referenced
from the XML structure described by gml:FileType. The external file is referenced by the
gml:fileReference property that is an anyURI (the gml:fileName property has been
deprecated). This means that the external file may be located remotely from the referencing
GML instance. The gml:compression property points to a definition of a compression algorithm
through an anyURI. This may be a retrievable, computable definition or simply a reference to
an unambiguous name for the compression method. The gml:mimeType property points to a
definition of the file mime type. The gml:fileStructure property is defined by a codelist.
Note further that all values shall be enclosed in a single file. Multi-file structures for
values are not supported in GML. The semantics of the range set is described as above using
the gml:rangeParameters property. Note that if any compression algorithm is applied, the
structure above applies only to the pre-compression or post-decompression structure of the
file. Note that the fields within a record match the gml:valueComponents of the
gml:CompositeValue in document order.