        <p>
                    Specifies that the grammar recognized by the regular expression
                    engine is the same as that used by POSIX extended regular expressions
                    in IEEE Std 1003.1-2001, Portable Operating System Interface
                    (POSIX ), Base Definitions and Headers, Section 9, Regular Expressions
                    (FWD.1).
                  </p>
                  <p>
                    Refer to the <a class="link" href="../../syntax/basic_extend