Take the use case, "User browses through the subject headings in a
database."

To meet this use case, I want to extract all the headings indexed as
dc.subject and display them at once (or in a paginated form).  I'm getting
only the full dc.subject headings, not the separate terms that make up the
headings.

The SRU scan operation requires me to submit a scanClause consisting of a
complete CQL search clause:  index, relation, and searchTerm.  Working
from the explanation here:

http://www.loc.gov/standards/sru/scan/

I'm assuming that use of the "exact" relation in this context is intended
to return full subject headings containing the searchTerm, so that
"dc.subject exact durham" would return both "Durham (N.C.)" and
"Architecture -- North Carolina -- Durham".  Please correct me if I've
misread this point.

But here's my real question:  is there no way within the SRW/U
specification to extract all or an arbitrary portion of the dc.subject (or
other) headings in a database without first sending a term to scan for?

I can think of ways to build/configure my SRU implementation to get what I
want, I'm just wondering if I'm _supposed_ to be able to use scan (or
another operation) to do this directly.

Thanks,

Will
--
Will Sexton
Metadata Architect / Programmer
Duke University Libraries