Roger,
Standard Identifier is really a separate index for most servers.
For LC, for example, Standard Identifier includes ISBN, ISSN, 
as well as LCCN.  While is it also possible to search each of
those separately.

  <index id="7">
    <title>isbn</title> 
      <map>
        <name set="bath">isbn</name> 
      </map>
  </index>
  <index id="8">
    <title>issn</title> 
      <map>
        <name set="bath">issn</name> 
      </map>
  </index>
  <index id="9">
    <title>lccn</title>
      <map>
        <name set="bath">lccn</name>
      </map>
  </index>
  <index id="1007">
    <title>standardIdentifier</title> 
      <map>
        <name set="bath">standardIdentifier</name> 
      </map>
      <map>
        <name set="dc">resourceIdentifier</name> 
      </map>
  </index>

It's complicated because the Standard Identifier search is
part of the Bath Profile, but the ISBN and the ISSN searches
are part of the US Profile which is an extension to Bath.

http://www.niso.org/standards/resources/Z39_89final.pdf

We support both with the "bath" prefix.
(I also see that LC is not current with regard to the 
appropriate name for the DC identifier -- we still use
"dc.resourceIdentifier" and don't yet support "dc.identifier".)

Hope that's somewhat helpful.
Larry


On Mon, 20 Aug 2007, Mike Taylor wrote:

> Interesting one.  I _think_ that the ZeeRex fragment you included
> below is Just Plain Wrong, and that you can't have the same index name
> occurring within two <map>s, but that's really a question for Rob
> Sanderson, who led the ANSI/NISO-Z39.92 standardisation of ZeeRex.
> 
> Rob?
> 
>  _/|_	 ___________________________________________________________________
> /o ) \/  Mike Taylor    <[log in to unmask]>    http://www.miketaylor.org.uk
> )_v__/\  "Unhappily, it coincided with Gascoigne attempting to set fire
> 	 to best friend Jimmy 'Five Bellies' Gardner's nose in a Newcastle
> 	 nightclub" -- The Guardian, 13th September 1998
> 
> 
> 
> Roger Wallin writes:
>  > Thanks for the answer,
>  > 
>  > before I continue, you should know that I have just started to work with 
>  > these concepts so there could be really easy answers, as I haven't 
>  > necessarily yet understood the whole concept.
>  > 
>  > So concerning "DC.identifier" I should just make an assumption that it 
>  > searches in some of the server indexes (chosen by us) and there doesn't 
>  > have to be any descriptions, at least none standardized description of 
>  > this assumption?
>  > 
>  > I have been told to use the XML below, but isn't this wrong as it says 
>  > that "DC.identifier" is the same as ISBN and ISSN, and those are actually 
>  > completely different indexes?
>  > Or does it say that searching for DC.identifier the access point is both 
>  > ISBN and ISSN?
>  > 
>  > I'm probably thinking too mathematical....
>  > 
>  >   Regards RogerW.
>  > 
>  > 
>  > <index id="7">
>  >   <title>isbn</title> 
>  >   <map>
>  >     <name>isbn</name> 
>  >   </map>
>  >   <map>
>  >     <name set="bath">isbn</name> 
>  >   </map>
>  >   <map>
>  >     <name set="DC">identifier</name> 
>  >   </map>
>  > </index>
>  > <index id="8">
>  >   <title>issn</title> 
>  >   <map>
>  >     <name>issn</name> 
>  >   </map>
>  >   <map>
>  >     <name set="bath">issn</name> 
>  >   </map>
>  >   <map>
>  >     <name set="DC">identifier</name> 
>  >   </map>
>  > </index>
>