Talk:Expressions

@Uwestoehr: Good catch, there are indeed many more characters allowed. If you give a negative list, then please extend it to other non allowed characters as well, mainly of course the frequently used blank, but there are of course many more. We have recently even seen that some Korean characters can create problems, so we should consider if it wouldn't be better to give a positive list. If not, please list or describe the characters to be excluded.