Ok! I'll continue on the same theme.
I found the following statement:
"However for bibliographic and cross domain searching, the 'Standard 
Identifier' (DC.identifier) access point is used for ISSN, ISBNs, ISMNs, 
LCCNs, etc."

Can I use DC.identifier to access both the isbn- and issn-index and how 
should this be explained in the XML below? 

If not, how should a new index "identifierAll" be explained that is 
a "union" of isbn and issn, ie.
  
query=isbn="x" or issn="x"
is the same as
query=identifierall="x"

 Regards RogerW.


<index id="7">
  <title>isbn</title> 
  <map>
    <name>isbn</name> 
  </map>
  <map>
    <name set="bath">isbn</name> 
  </map>
</index>
<index id="8">
  <title>issn</title> 
  <map>
    <name>issn</name> 
  </map>
  <map>
    <name set="bath">issn</name> 
  </map>
</index>