namespace xrds = "xri://$xrds"
namespace xrd = "xri://$xrd*($v*2.0)"
namespace local = ""
datatypes xs = "http://www.w3.org/2001/XMLSchema-datatypes"

any.element =
  element *  {
    (attribute * { text } *
     | text
     | any.element)*
  }
  
any.external.element =
  element * - (xrd:XRD | xrds:XRDS)  {
    (attribute * { text } *
     | text
     | any.element)*
  }
  
other.attribute = attribute * - (local:*) {text}

start = XRDS

XRDS = element xrds:XRDS {
    other.attribute *,
    (attribute ref { xs:anyURI } | attribute redirect { xs:anyURI} )?,
    (any.external.element  | XRDS | external "xrd.rnc" )*
}