-ec ::= [~\]\\\-\~] | escaped
-
-alternatives ::= equiAlt +/ (ws ">" ws)
-equiAlt ::= conjuncts +/ (ws "|" ws) => "alternatives"
-
-sequence ::= Es
- > Es ^"/" e /ws
-Es ::= e+
-es ::= e+/ws
-
-conjuncts ::= rewrite
- | rewrite ^"&" sequence /ws
- | rewrite ^"&~" sequence /ws