module languages/sdf2/idioms/FirstLayout exports sorts ABC lexical syntax [\ \t\n] -> LAYOUT context-free start-symbols ABC context-free syntax "a" "b"? "c" -> ABC %% without the restriction, the term: %% a c %% is ambiguous because the space can be attributed %% in between "a" and "b"?, or in between "b"? and "c" context-free restrictions LAYOUT? -/- [\ \t\n]