How to use specific unicode characters in regular expressions ?

I am struggling with a search & replace for French typography for the compile stage.
I would like to use something like \xA0 or \u00A0 (for a non-breaking space) but it fails whatever I try
I grabbed that Scrivener is using an engine based upon Perl Compatible Regular Expressions (PCRE) guidelines
So it should work, but I can’t find a way of getting to that point.

Thanks for sharing your thoughts

Perl uses the syntax \x{FFFF} for Unicode characters (U+FFFF), so you should be able to do this by searching for \x{00A0}. If you’re trying to replace with the whitespace character, the RegEx won’t work; just copy and paste an example non-breaking space into the field, or use Opt-space to type it in.