A.2 Basic Specifications with Subsorts

SORT-ITEM        ::= ... | SUBSORT-DECL | ISO-DECL | SUBSORT-DEFN

SUBSORT-DECL     ::= subsort-decl SORT+ SORT
ISO-DECL         ::= iso-decl SORT+
SUBSORT-DEFN     ::= subsort-defn SORT VAR SORT FORMULA

ALTERNATIVE      ::= ... | SUBSORTS
SUBSORTS         ::= subsorts SORT+

ATOM             ::= ... | MEMBERSHIP
MEMBERSHIP       ::= membership TERM SORT

TERM             ::= ... | CAST
CAST             ::= cast TERM SORT