RFC 2056 (rfc2056) - Page 2 of 7

Uniform Resource Locators for Z39

RFC 2056                    URLs for Z39.50                November 1996


   parse otherwise opaque parts of the URL (consistent with current
   practice).

2. Some Basic Concepts

   This section briefly describes the usage of Z39.50-specific
   terminology within the URL definitions below: specifically, the terms
   database, elementset, recordsyntax, and docid.

   The Z39.50 protocol specifies various information retrieval
   operations, the two most basic of which are Search and Present. In a
   Search operation a client provides search criteria and indicates a
   database (or several databases) on the server to search.  The
   essential result of a Search operation is that a result set is
   created at the server, consisting of pointers to the selected
   database records.

   Z39.50 models database records, abstract database records, and
   retrieval records.  A database record is a unit of information in a
   database, represented in a data structure local to the server.  An
   abstract database record is an abstract representation of that
   information, where the client and server share a common understanding
   of the representation.  This allows logical elements to be addressed
   and selected for transfer, via an element set specification, or, as
   used below, an "elementset".  A retrieval record is the set of
   selected elements packaged in an exportable structure, by the
   application of a "recordsyntax".

   Thus a Search operation results in entries pointing to database
   records; via a Present operation, a client requests a retrieval
   record, corresponding to a database record, corresponding to an entry
   in the result set. The client indicates the composition and format of
   the retrieval record by specifying an elementset and recordsyntax,
   respectively.

   A special case of a Z39.50 search is a "known-item" search, when a
   client intends that a search identify a single, known database
   record, or "document" (for purposes of illustration, assume that a
   database record corresponds to a document), and further, the client
   knows an identifier for the document that can be used to effect this
   known-item search.  In this case, this identifier is often referred
   to as a document identifier, or "docid".









Denenberg, et. al.          Standards Track