dbhtml_dir — Specifies a directory name in which to write files
<?dbhtml dir="path"?>When chunking output, use the <?dbhtml dir?> PI
      as a child of a chunk source to cause the output of that
      chunk to be written to the specified directory; also, use it
      as a child of a mediaobject to specify a
      directory into which any long-description files for that
      mediaobject will be written.