Encoding a GML property inline vs. by-reference shall not imply anything about
the “ownership” of the contained or referenced GML Object, i.e. the encoding style shall not
imply any “deep-copy” or “deep-delete” semantics. To express ownership over the contained or
referenced GML Object, the gml:OwnershipAttributeGroup attribute group may be added to
object-valued property elements. If the attribute group is not part of the content model of
such a property element, then the value may not be “owned”. When the value of the owns
attribute is "true", the existence of inline or referenced object(s) depends upon the
existence of the parent object.