The unit of measure for volume or mass loss. Can be a volume ratio (m3/m3, %, etc.) or a mass ratio (kg/kg, %, etc.). The choice depends on whether volume change or mass change is being measured.
Database handle for the object. It is of XML type ID, so is constrained to beunique in the XML document within which it occurs. An external identifier for the object inthe form of a URI may be constructed using standard XML and XPointer methods. This is doneby concatenating the URI for the document, a fragment separator, and the value of the idattribute.