XSL question

Could someone help me with this

I have an XSL which does transformation of XML  to  XML 


input XML  ---- ( xsl ) ------ Output XML 


During this process the XSL should  have access to two configuration file
XXXvalues.xml,  YYYvalues.xml  and pick only one based on 
an warehouseid  tag coming in the input XML and use values inside the picked
configuration file to build the output XML


For example if the <warehouseid>XXX<warehouseid> in input XML then use a
configuration file XXXvalues.xml 

or  if  <warehouseid>YYY<warehouseid> in input XML then use configuration
file  YYYvalues.xml 

Can some one let me know how I can achieve this. 


Thanks in advance 
Harsha 


ps:

I have in the past worked on a single configuration file to extract values
but it did not have any logical evaluation

<xsl:variable name="BillTo" select="document('../../BillToConfig.xml')"/>