(*
(**) fix pair notation
notation > "hvbox( { term 46 hd1, break term 46 hd2 }⨮{ break term 46 S1, break term 46 S2 } break term 46 tl )"
non associative with precedence 47
(*
(**) fix pair notation
notation > "hvbox( { term 46 hd1, break term 46 hd2 }⨮{ break term 46 S1, break term 46 S2 } break term 46 tl )"
non associative with precedence 47