-PreSequence ::= Elements => "ps"
- | PreSequence !wp ^"/" !ws e
- | PreSequence ^"->" e /ws
- | (Quoted|word) ^"::" PreSequence /ws
- | PreSequence ^"=>" ("[]"|"()"|word|Quoted) /ws
-Sequence ::= PreSequence => "psx"
+NonTerminal = Word "=" RHS /ws
+ | Word "*" ws! ^"=" ws! RHS
+ | Word "*/" Word ws! ^"=" ws! RHS
+
+RHS = (Sequence +/ (ws! "|" ws!)) +/ (ws! ">" ws!)