Reference for “XML Signature Properties”

@TechReport{Hirsch:09:XSP,
  author      = "Frederick Hirsch",
  title       = "{XML} Signature Properties",
  month       = apr,
  note        = "http://www.w3.org/TR/2009/WD-xmldsig-properties-20090430/",
  year        = "2009",
  bibsource   = "http://w2.syronex.com/jmr/w3c-biblio",
  type        = "{W3C} Working Draft",
  institution = "W3C",
}