+<sect1>Z39.50 Protocol Support and Behavior
+
+<sect2>Initialization
+
+<p>
+During initialization, the server will negotiate to version 3 of the
+Z39.50 protocol, and the option bits for Search, Present, Scan,
+NamedResultSets, and concurrentOperations will be set, if requested by
+the client. The maximum PDU size is negotiated down to a maximum of
+1Mb by default.
+
+<sect2>Search
+
+<p>
+The supported query type are 1 and 101 All operators except PROXIMITY
+are currently supported. Queries can be arbitrarily complex. Named
+result sets are supported, and result sets can be used as operands
+with no limitations. Searches may span multiple databases.
+
+The server has full support for piggy-backed present requests (see
+also the following section).
+
+<bf/Use/ attributes are interpreted according to the attribute sets which
+have been loaded in the <tt/zebra.cfg/ file, and are matched against
+specific fields as specified in the <tt/.abs/ file which describes the
+profile of the records which have been loaded. If no <bf/Use/
+attribute is provided, a default of <bf/Any/ is assumed.
+
+If a <bf/Structure/ attribute of <bf/Phrase/ is used in conjunction with a
+<bf/Completeness/ attribute of <bf/Complete (Sub)field/, the term is
+matched against the contents of a phrase (long word) register, if one
+exists for the given <bf/Use/ attribute. If <bf/Structure/=<bf/Phrase/
+is used in conjunction with <bf/Incomplete Field/ - the default value
+for <bf/Completeness/, the search is directed against the normal word
+registers, but if the term contains multiple words, the term will only
+match if all of the words are found immediately adjacent, and in the
+given order. If the <bf/Structure/ attribute is <bf/Word List/,
+<bf/Free-form Text/, or <bf/Document Text/, the term is treated as a
+natural-language, relevance-ranked query.
+
+If the <bf/Relation/ attribute is <bf/Equals/ (default), the term is
+matched in a normal fashion (modulo truncation and processing of
+individual words, if required). If <bf/Relation/ is <bf/Less Than/,
+<bf/Less Than or Equal/, <bf/Greater than/, or <bf/Greater than or
+Equal/, the term is assumed to be numerical, and a standard regular
+expression is constructed to match the given expression. If
+<bf/Relation/ is <bf/Relevance/, the standard natural-language query
+processor is invoked.
+
+For the <bf/Truncation/ attribute, <bf/No Truncation/ is the default.
+<bf/Left Truncation/ is not supported. <bf/Process #/ is supported, as
+is <bf/Regxp-1/. <bf/Regxp-2/ enables the fault-tolerant (fuzzy)
+search. As a default, a single error (deletion, insertion,
+replacement) is accepted when terms are matched against the register
+contents.
+
+<sect2>Present
+
+<p>
+The present facility is supported in a standard fashion. The requested
+record syntax is matched against the ones supported by the profile of
+each record retrieved. If no record syntax is given, SUTRS is the
+default. The requested element set name, again, is matched against any
+provided by the relevant record profiles.
+
+<sect2>Scan
+
+<p>
+The attribute combinations provided with the TermListAndStartPoint are
+processed in the same way as operands in a query (see above).
+Currently, only the term and the globalOccurrences are returned with
+the TermInfo structure.
+
+<sect2>Close
+
+<p>
+If a Close PDU is received, the server will respond with a Close PDU
+with reason=FINISHED, no matter which protocol version was negotiated
+during initialization. If the protocol version is 3 or more, the
+server will generate a Close PDU under certain circumstances,
+including a session timeout (60 minutes by default), and certain kinds of
+protocol errors. Once a Close PDU has been sent, the protocol
+association is considered broken, and the transport connection will be
+closed immediately upon receipt of further data, or following a short
+timeout.
+