my $nfw_oang = qr%    
   (?!
      \p{IsOang}
      (?! (?:\p{InThaiFinCons}){1,2}
          (?[
             \p{InThaiMute}
             - \p{InThaiCompVowel}
             - \p{InThaiPostVowel}
             - \p{InThaiTone}
          ])
      )
   )
%x;