+=head2 Scan handler
+
+A full featured Z39.50 server should support scan (or in some literature
+browse). The client specifies a starting term of the scan, and the server
+should return an ordered list of specified length consisting of terms
+actually occurring in the data base. Each of these terms should be close
+to or equal to the term originally specified. The quality of scan compared
+to simple search is a guarantee of hits. It is simply like browsing through
+an index of a book, you always find something! The parameters exchanged are
+
+ $args = {
+ ## Client request
+
+ HANDLE => $ref ## Reference to data structure
+ TERM => 'start', ## The start term
+ NUMBER => xx, ## Number of requested terms
+ POS => yy, ## Position of starting point
+ ## within returned list
+ STEP => 0, ## Step size
+
+ ## Server response
+
+ ERR_CODE => 0, ## Error code
+ ERR_STR => '', ## Diagnostic message
+ NUMBER => zz, ## Number of returned terms
+ STATUS => $status, ## ScanSuccess/ScanFailure
+ ENTRIES => $entries ## Referenced list of terms
+ };
+
+where the term list is returned by reference in the scalar $entries, which
+should point at a data structure of this kind,
+
+ my $entries = [
+ { TERM => 'energy',
+ OCCURRENCE => 5 },
+
+ { TERM => 'energy density',
+ OCCURRENCE => 6, },
+
+ { TERM => 'energy flow',
+ OCCURRENCE => 3 },
+
+ ...
+
+ ...
+ ];
+
+The $status flag should be assigned one of two values:
+
+ Net::Z3950::SimpleServer::ScanSuccess On success (default)
+ Net::Z3950::SimpleServer::ScanPartial Less terms returned than requested
+
+The STEP member contains the requested number of entries in the term-list
+between two adjacent entries in the response.
+