Any information on which standard they have implemented (POSIX BRE, ERE, PCRE, ...)? Since they are Microsoft, I would not be surprised if there is none.
Okay, thanks! Now next question which comes into my mind: is there info about the regex engine they are using? I would expect there is some (proprietary?) C++ library also used in other MS products or are they even using a FOSS licensed one?
Seems likely that if they explicitly say they're supporting the PCRE2 syntax it is because they are using the BSD licensed libpcre.
Reinventing a regular expression system is very far down on the list of things I'd ever want to do. Those things are filled with dragons and require years of refinement to get the bugs out.
