ruby =
  element ruby {
    ruby.attlist,
    ((rb,
      (rt | (rp, rt, rp)))
     | (rbc, rtc, rtc?))
  }
ruby.attlist = Common.attrib
rbc = element rbc { rbc.attlist, rb+ }
rbc.attlist = Common.attrib
rtc = element rtc { rtc.attlist, rt+ }
rtc.attlist = Common.attrib
rb = element rb { rb.attlist, Inline.model }
rb.attlist = Common.attrib
rt = element rt { rt.attlist, Inline.model }
rt.attlist =
  Common.attrib,
  attribute rt { Number.datatype }?
rp = element rp { rp.attlist, text }
rp.attlist = Common.attrib
Inline.class |= ruby