An (optional) index into a system table used to specify
supplemental information for this device alert.
Usage: When xcmHrDevAlertReferenceOID is a table,
xcmHrDevAlertReferenceIndex can be an index into that table.
Note: If the ReferenceOID table has multiple indices, the
management table must recognize the table and must know which
index is given by this ReferenceIndex.
Usage: Use -1 if no index is required.