Scan: Boolean Expression

Dear ZIG,
I don't know if we ever will have a Z39.50 Version 4, or maybe a new
retrieval protocol, but if so, I would strongly suggest to allow a Boolean
expression in the Scan Request.
Not to combine term lists, but to apply the 2nd and further operand as a
restriction to the first. 
(I know that the notion of secondary search, or Restrictions, or Scoping, or
whatever you name it, does not exist in Z39.50. This has some advantages,
but also disadvantages.)

We would like to do a scan that returns only headings from a certain agency
or institution. Like:
Scan Title "whatever" AND CodeInstitution = "ABC"

or scan only serial publications:
Scan Title "whatever" AND Bib-level = "as"

(In fact, we don't want to do an AND, it is more an ONLY_WHEN: we want
heading from Title but only when the second condition is fulfilled.)

These kind of things are not possible.
The ScanRequest has an entry called "termListAndStartPoint" defined as
AttributesPlusTerm.
This does not allow to combine 2 or more Use attributes.

The easiest solution is to copy the RPNStructure from the Search Request.
But I think this is worth a more profound discussion.
Actually, when you think about it: a heading (scan entry) is a very strange
thing. 


Pieter van Lierop

Received on Thursday, 15 March 2001 11:38:21 UTC