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.
The relative significance of the constituent, with 1 the highest. Itremoves the ambiguity of inferring significance from abundanceCode.
Source
<element name="Constituent" type="diggs:ConstituentType"><annotation><documentation>A minor constituent within a lithology zone: its identity, abundance and distribution.</documentation></annotation></element>