Well, the six in question is a rather fuzzy number, but you can count things like \x{2639} and \N{WHITE FROWNING FACE} as a different category, plus curlies are used in formats to hide newlines in argument lists, though arguably that's also a code block. But in that case the primary intent is not to supply a code block, since the code in question is merely expected to return a list. Also, if I recall correctly, at one point you could replace the = and . surrounding a format with curlies, but that seems to be broken currently. The internals of toke.c still pretend that they are curlies though.