code: def to_reference_tags(src, dest)
        inpath = File.expand_path(src)
        outpath = File.expand_path(dest)
        xsltpath = File.dirname(__FILE__) + "/../../support/switch-onix-2.1-short-to-reference.xsl"
        `xsltproc -o #{outpath} #{xsltpath} #{inpath}`
      end
docs: uses an XSLT stylesheet provided by edituer to convert
   a file from short tags to long tags.
  
   more detail here:
     http://www.editeur.org/files/ONIX%203/ONIX%20tagname%20converter%20v2.htm