Issue raised by: Mike Taylor [email protected] Wed, 13 May 1998 17:50:24 +0100
If a Z39.50 retrieval schema is defined such that a record is to include an element indicating its unique id for subsequent retrieval in the manner of a Z39.50r url (RFC 2056), that is, with bib-1 Use attribute docid (1032) and structure attribute URx (104), is there any particular tagSet G or M element intended for this purpose?
The candidates appear to be tagSet-M element url (1,12) or localControlNumber (1,14), or tagSet-G element documentId (2,5) or identifier (2,28).
url (1,12) or localControlNumber (1,14) may be used for this purpose.
(Note that this should not be tagSet-G element. It should be a tagSet-M element because the information is metadata about the actual record in which the element resides. tagSet-G is oriented towards information that the record describes but which is information external to the actual record.)
Note the definition of structure attribute Urx (104): "The term is a document identifier, for example, an identifier extracted from a Z39.50 url."
If url (1,12) is used, the element may be the full url, and the document identifier part of the url may be extracted and used as the term in the search (this approach provides the client with the full url, for purposes external to Z39.50). Alternatively, if localControlNumber (1,14) is used, it should be only the document identifier part of the url.