For review: Revised Version *Element* Rules

Schema Rules:

    Every UBL schema module MUST capture its version number in the xsd:version attribute of the xsd:schema element.
    Every UBL document schema MUST include a required element named "UBLVersion" as the first child of it's root element. This element MUST have a default value that matches the value of the xsd:version attribute of its containing schema.

Instance Rule:

    The value of the 'UBLVersion' element MUST match the value of the xsd:version attribute of the UBL Document schema it instantiates.