+FileName = FileNameChar+ -> [\r\n ]
+FileNameChar = Space:: "\\ "
+ | ~[\r\n ]
+
+NonTerminal = Word "=" RHS /ws
+ | Word "*" ws! ^"=" ws! RHS
+ | Word "*/" Word ws! ^"=" ws! RHS
+
+RHS = (Sequence +/ (ws! "|" ws!)) +/ (ws! ">" ws!)
+
+Elements = e*/ws
+
+PreSequence = Elements
+ | (Quoted|Word) ^"::" PreSequence /ws
+ > PreSequence ^"/" e /ws
+ | PreSequence ^"->" e /ws
+
+Sequence = psx:: PreSequence
+ | Sequence ^"&" Elements /ws
+ | Sequence ^"&~" Elements /ws
+
+ec = ~[\-\]\\]