Posts’ and comments’ minimum length validations are being bypassed by the U+2800 BRAILLE PATTERN BLANK Unicode character "⠀". It counts as an "Other Symbol", not as whitespace or a control character.

For example, see the comment beneath this post.

This needs to be fixed.

  • 7
    – user707129
    Nov 1, 2019 at 19:53
  • 2
    @fixer1234 it is a bug and needs to be fixed
    – user707129
    Nov 1, 2019 at 19:58
  • 3
    Is it really such an issue though? How often those this cause problems? Nov 1, 2019 at 20:06
  • 9
    There is an endless series of characters that will, eventually, render thusly. For example, ͏ (U+034F) which is also blank and zero width to boot (see next comment): Nov 1, 2019 at 20:14
  • 6
    ͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏ Nov 1, 2019 at 20:15
  • 5
    – tchrist
    Nov 1, 2019 at 20:33

1 Answer 1


Such measures are pointless.

  1. Someone finding obscure Unicode characters to bypass filters won't be stopped by banning of any specific character. Even if you ban every non-ASCII character, there's good old underscore. Serves same purpose, just isn't as pretty.

  2. Unicode is constantly updated. It's incredibly tedious to keep up with it. Hint: there're already more characters like this.

  3. Last time filters were updated, legitimate formatting with unbreakable spaces became impossible. Let's not make the problem even worse.

  • 4
    This is not true. Unicode isn't just numbers. It has rules, and new code points will always have analysable properties that allow you to write stable code even though those new codepoints haven't been defined yet. So for example if the intent of the rule is that the string be at least 15 printable extended grapheme clusters in column-width, then this is trivially calculated using the UAX#29 Text Segmentation algorithm. That way something like Ḉṝǡṥş̃̈ and Ḉṝǡṥş̃̈ both count as width=5 rather than 16 for the first or 7 for the second.
    – tchrist
    Nov 1, 2019 at 23:30
  • 2
    @tchrist The only thing you can check is not Alpha because U+2800 isn't WSpace, isn't collapsed by any normalization and isn't zero-width. However, such check would be too restricting. Users of math sites won't appreciate this.
    – Athari
    Nov 2, 2019 at 5:26