Thank you to all who responded. Using bath.isbn does, in fact, work as expected. I did see another peculiarity which I need to grapple with — namely that different editions of the book (e.g., hardcover and paperback) will have different ISBNs, but not all of them will be registered with LoC. For example, one of my “test” books was an example of this; the hardcover edition was found, but the paperback edition (which is the one I was testing with) was not. This has design (or at least help-system) consequences for my application. Has anyone found a solution for this problem? Cheers, Rick On Aug 8, 2014, at 3:40 PM, LeVan,Ralph <[log in to unmask]<mailto:[log in to unmask]>> wrote: The Explain record is telling you that the isbn index is from the “bath” context set. Think of context sets like namespaces in XML. They’re trying to help you avoid name collisions. Change the index name in your query to “bath.isbn” and it will work just fine. http://z3950.loc.gov:7090/voyager?version=1.1&operation=searchRetrieve&query=bath.isbn=9781449313944 Returned: <zs:searchRetrieveResponse xmlns:zs="http://www.loc.gov/zing/srw/"> <zs:version>1.1</zs:version> <zs:numberOfRecords>1</zs:numberOfRecords> </zs:searchRetrieveResponse> Ralph From: SRU (Search and Retrieve Via URL) Implementors [mailto:[log in to unmask]] On Behalf Of Rick Aurbach Sent: Friday, August 08, 2014 4:04 PM To: [log in to unmask]<mailto:[log in to unmask]> Subject: SRU - can I do a lookup via ISBN? I am an utter newbie to SRU and would be very grateful for your help. I am trying to implement an application in which the user (a) first scans an ISBN from a book, then (b) does a lookup via SRU to get information from the Library of Congress (and thereby avoid manual entry). I am using (for example) http://z3950.loc.gov<http://z3950.loc.gov/>:7090/voyager?version=1.1&operation=searchRetrieve&query=isbn=9781449313944 and I am getting back: numberOfRecords: 0 diagnostic: message: Unsupported index detail: isbn However, if I get the Explain record, it says <index id=“7”> <title>isbn</title> <map><name set=“bath”>isbn</name></map> </index> So I would have thought that what I attempted to do was legal.  What am I missing here?  How can I do an ISBN lookup? Thank you for your help. Cheers, Rick Aurbach Aurbach & Associates, Inc.