I am testing out security and reliability issues on my site. I have made \n and \r illegal. I created a user with null in the name which caused my PM system to not message the user. However \b worked and \t didnt allow copy/paste to work correctly. The browser (firefox which i am testing with) copied the tab as a single space causing the name not to be the same thus not recognizing the username. Since i cant copy paste easily i'll probably disallow it. \f works as well although i do see a symbol in the title but nowhere else because of the \f.

What else should i try? It appears 0-31 127-159 (i dont understand this range) are illegal. What characters in legal range might i want to disallow? I heard there was a 0 width character space. That may be something i want to disallow? What else is there?