key provides an external means
of locating a full definition for the entity (or entities) being named, such as a database record key
or other token.Zustand Optional Datentyp Vom kompakten zum XML-Format Vom XML-Format zum kompakten <rng: ref name ="data.key "/>
data.key Werte any string of Unicode characters
ref (reference) provides an explicit means
of locating a full definition for the entity being named by means of
a URI.Zustand Optional Datentyp 1–∞ Vorkommen von Durch Leerzeichen getrennt Werte any valid URI
nymRef (reference to the canonical name) provides a means of locating the canonical form
(nym ) of the names associated with the object
named by
the element bearing it.Zustand Optional Datentyp 1–∞ Vorkommen von Durch Leerzeichen getrennt Werte any valid URI