causes the pattern itself and all data
strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF
is not part of the POSIX standard.
</p>
<p>
In the absence of these flags, no options are passed to the native function.
This means that the regex is compiled with PCRE2 default semantics. In
particular, the way it handles newline characters in the subject string is the
Perl way, not the POSIX way. Note that setting PCRE2_MULTILINE has only
<i>some</i> of the effects specified for REG_NEWLIN