One you could use would be TAB if you're not needing that elsewhere. Not sure about others.
Since I don't talk in channels that use non-English characters, whenever I need to replace text, I will just use a character that isn't going to be used normally. Something like × or Ø or Þ or something similar. If I'm replacing something that others may use in channels that use these types of characters, then I typically pick some "random" combination of 3 of those kinds of characters or else just 3 symbols that are unlikely to be used together. This works well, but it does mess up $len/$right/$left/$mid/etc if you need to use those. Of course, that can also be worked around if needed. If those really aren't needed, then this is usually a "safe" way to handle such temporary replacements.
