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(unknown charset) Re: Z39.50 Searching

From: (unknown charset) Larry E. Dixson <ldix@loc.gov>
Date: Fri, 17 Sep 2004 11:22:32 -0400 (EDT)
To: (unknown charset) www-zig@w3.org
Message-ID: <Pine.SOL.4.21.0409171056460.18179-100000@sun8.loc.gov>

On Thu, 16 Sep 2004, Heiko Jansen wrote:
> Am Mittwoch, 15. September 2004 20:29 schrieb Slavko Manojlovich 
> <slavko@mun.ca> [RE: Z39.50 Searching]:
> 
> > I thought that structure = wordlist was deprecated because it supported
> > default behaviour vis a vis the application operators on the server side.
> > Some servers default to "AND" and other servers default to "SAME FIELD".
> > Ideally, you would send this search as structure = 2 with the "AND"
> > operator.
> 
> Seems to be bad luck for me: I was hoping I could tell the server implementors 
> to change their servers´ behaviour, but if there is no exact definition of 
> how a server should react to such queries my negotiating position seems quite 
> weak.

Heiko,
There is a document, that is not part of the standard, that
contains some Bib-1 attribute semantics.  You can find the
document at the following address:

ftp://ftp.loc.gov/pub/z3950/defs/bib1.txt

Quoting from that document, a "Word list" is described as follows:

    "A word list consists of one or more words separated by blanks
     . . . No order of the words is implied.  The attributes (other
     than structure) that are associated with the search term
     apply to each word in the word list.  Any words in a word list
     may be explicitly truncated . . . The relationship between
     the words in a word list is target-specific."

Slavko is correct, word list search terms may be processed 
differently by different targets.  In order to gain more
control of how your search is processed, you should use
single-word search terms and specify the Boolean operator
_you_ want the target to apply.


 
> I´m still wondering, however, what is really meant by the terms 
> "field"/"subfield"?
> Since Z39.50 provides an abstraction layer for searching and the record 
> syntaxes are decoupled from the search indices: how am I supposed to find out 
> what fields and subfields there are?
> Could anyone provide me with a definition of these terms or point me to a 
> discussion of this topic?

The Bib-1 document cited above contains a similar paragraph 
in the Position attribute section and in the Completeness
attribute section.  

   "For the purpose of describing the -------- attribute, when
    the expressions 'field' and 'subfield' do not have another
    understood meaning (as prescribed, for example, by the
    schema in use), these two expressions are used as follows:

        - 'subfield' has no meaning, and the -------- attribute
          'first in any subfield' is not to be used.
        - 'field' refers to the portion of the record to which
          the access point refers."


Hope that helps somewhat.
Larry

------------------------------------------------------------
Larry E. Dixson                    Internet:    ldix@loc.gov
Network Development and MARC
   Standards Office, LM639
Library of Congress                Telephone: (202) 707-5807
Washington, D.C.  20540-4402       Fax:       (202) 707-0115
Received on Friday, 17 September 2004 15:23:06 GMT

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