-conjuncts ::= sequence
- | sequence ^"&" e*/ws /ws
- | sequence ^"&~" e*/ws /ws
-
-ps ::= e*/ws => "ps"
-psx ::= ps
- > ps ^"/" e /ws
-sequence ::= psx
- | psx ^"=>" (word|quoted) /ws
+conjuncts ::= sequence
+ | sequence ^"&" e*/ws /ws
+ | sequence ^"&~" e*/ws /ws
+
+ps ::= e*/ws => "ps"
+ | (e+/ws ws)? "^" quoted (ws e+/ws)? => "ps2"
+psy ::= ps
+ | ps wp ^"/" ws e
+psx ::= psy ^"?=>" e /ws
+ | psy ^"!=>" e /ws
+ > psy
+sequence ::= quoted => "qprod"
+ > psx
+ | psx ^"=>" (word|quoted) /ws