R    Set CR as the newline sequence
  PCRE_NEWLINE_CRLF  Set CRLF as the newline sequence
  PCRE_NEWLINE_LF    Set LF as the newline sequence
  PCRE_NOTBOL        Subject is not the beginning of a line
  PCRE_NOTEOL        Subject is not the end of a line
  PCRE_NOTEMPTY      An empty string is not a valid match
  PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
                       validity (only relevant if PCRE_UTF8
                       was set at compile time)
  PCRE_PARTIAL       Return PCRE_E