notation "hvbox (r \sub \c)" with precedence 90 for @{'concr_rel $r}.
notation "hvbox (r \sub \f)" with precedence 90 for @{'form_rel $r}.
notation "hvbox (r \sub \c)" with precedence 90 for @{'concr_rel $r}.
notation "hvbox (r \sub \f)" with precedence 90 for @{'form_rel $r}.