sig
  type physical_materialized_type = PT_CSeq | PT_LSeq
  type physical_xml_type =
      PT_Mat of Xquery_algebra_ast_annotation.physical_materialized_type
    | PT_Sax
  type physical_tuple_type =
      (Xquery_common_ast.cvname *
       Xquery_algebra_ast_annotation.physical_xml_type)
      list
  type physical_type =
      PT_XML of Xquery_algebra_ast_annotation.physical_xml_type
    | PT_Table of Xquery_algebra_ast_annotation.physical_tuple_type
end