added variable file-ref

usas-annotation/insert-usas-annotations.xsl

@@ -44,9 +44,10 @@
     <!-- Templates -->
     <xsl:template match="/">
         <xsl:for-each select="distinct-values($wmatrix-utterances//*:u/@file-ref)"> 
+            <xsl:variable name="file-ref" select="." as="xs:string"/>
             <!-- overwrite the document -->
-            <xsl:for-each select="document(.)">
-              <xsl:result-document href="{.}">
+            <xsl:for-each select="document($file-ref)">
+              <xsl:result-document href="{$file-ref}">
                       <xsl:apply-templates/>
               </xsl:result-document>     
             </xsl:for-each>