specifying file extension for result files

usas-annotation/insert-usas-annotations.xsl

@@ -35,6 +35,7 @@
             <xsl:copy-of select="document(.)//*:u"/>
         </xsl:for-each>
     </xsl:variable>
+    <xsl:variable name="result-files-extension" select="'.exbu'"/>
     
     <!-- Keys -->
     <xsl:key name="words" match="w" use="concat(../@file-ref, '#', ../@tier-category, '#', ../@speaker, '#', ../@start, '#', ../@end)"/>
@@ -48,7 +49,7 @@
             <xsl:variable name="doc" select="document($file-ref)"/>
             <!-- overwrite the document -->
             <xsl:for-each select="$doc">
-               <xsl:result-document href="{$file-ref}.usas">
+               <xsl:result-document href="{concat(replace($file-ref, '\.exb$', ''), $result-files-extension)}">
                       <xsl:apply-templates/>
                </xsl:result-document>     
             </xsl:for-each>