Yes. Though there's lots of other flavours as well.
There's a few interesting additions you can make to POSIX style regex that preserve the linear runtime: eg complement, difference or intersection of regular expression, see eg https://docs.rs/regex/1.3.9/regex/#syntax
And there's lots of other backtracking-mandatory features that you see in some non PCRE flavours.
Comments
Yes. Though there's lots of other flavours as well.
There's a few interesting additions you can make to POSIX style regex that preserve the linear runtime: eg complement, difference or intersection of regular expression, see eg https://docs.rs/regex/1.3.9/regex/#syntax
And there's lots of other backtracking-mandatory features that you see in some non PCRE flavours.