owing macros:
<pre>
  REG_DOTALL
</pre>
The PCRE2_DOTALL option is set when the regular expression is passed for
compilation to the native function. Note that REG_DOTALL is not part of the
POSIX standard.
<pre>
  REG_ICASE
</pre>
The PCRE2_CASELESS option is set when the regular expression is passed for
compilation to the native function.
<pre>
  REG_NEWLINE
</pre>
The PCRE2_MULTILINE option is set when the regular expression is passed for
compilation to the native function. Note that this does <i>not</i> m