| key | provides an external means
of locating a full definition for the entity being named, such as a database record key
or other token.| Status | Optional | | Datatype | | | Values | any string of Unicode characters | | Note | The value may be a unique identifier from a database, or
any other externally-defined name for the referent. |
|
| ref | (reference) provides an explicit means
of locating a full definition for the entity being named by means of
a URI.| Status | Optional | | Datatype | | | Values | any valid URI | | Note | The value must point directly to an XML element containing
the corresponding information, located within the current
document or elsewhere and acccessible by a 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.| Status | Optional | | Datatype | 1–∞ occurrences of separated by whitespace | | Values | any valid URI | | Note | The value must point directly to an XML element containing
the corresponding information, located within the current
document or elsewhere and acccessible by a URI. |
|