Refer to this thread as an example:

https://community.sdl.com/product-groups/translationproductivity/f/171/p/21196/73595#73595

Sometimes the regular expression you need to create to tag the non-translatable content can be very complex.  For example, in this source text only the red text should be translated:

<li>Klicken Sie {{clik|ff|OK}} und {{clik|OK}}.</li>
==some text here {{click|..\path}} bzw {{click|..\path}} some other text here.==

<ol>some text here [[click|..\path]] bzw [[click|text|..\path]] some other text here.</ol>

This is a bit of an extreme example, but it does present the solution I'm asking for quite well.  The regex required in this case was this:

(?:[^OK.\\path]|O(?!K)|(?<!O)K|\.(?!\.?\\path)|\\(?!path)|(?<!\.\.)\\|p(?!ath)|(?<!\.\.\\)p|a(?!th)|(?<!\.\.\\p)a|t(?!h)|(?<!\.\.\\pa)t|(?<!\.\.\\pat)h)+

If there was a negation option on the filetype settings (as we have in the Community Advanced Display Filter) you would only need this:

OK|\.\.\\path

If the source material starts to vary, and I have a suspicion it will, the current solution quickly becomes unworkable and even more complex than it already is.  The negation option would simplify it immensely and remove the likelihood of mistakes.