Untangling Tables

html.table =
   element table {
      attribute frame {
         "void"   | "above"  | "below"
       | "hsides" | "vsides" | "lhs"
       | "rhs"    | "box"    | "border" }?,
      ((html.thead?, html.tfoot?, html.tbody)
       | html.tr+)
   }

html.tbody =
   element tbody { html.tr+ }