?SRH    Search failure "text"

          A search command not preceded by a  colon  modifier
          and  not within an iteration has failed to find the
          specified "text".  After  an  S  search  fails  the
          pointer  is  left  at  the beginning of the buffer.
          After an N or _ search fails the last page  of  the
          input  file  has  been input and, in the case of N,
          output, and the buffer is cleared.  In the case  of
          an  N  search  it is usually necessary to close the
          output file and reopen it for continued editing.