ss="c">!              IN WHICH THE VARIABLE NAME      X    IS USED</span>
<span class="c">!              AS BOTH THE FIRST AND FOURTH ARGUMENTS.</span>
<span class="c">!     ORIGINAL VERSION--NOVEMBER  1974.</span>
<span class="c">!     UPDATED         --APRIL     1975.</span>
<span class="c">!     UPDATED         --NOVEMBER  1975.</span>
<span class="c">!</span>
<span class="c">!---------------------------------------------------------------------</span>
<span class="c">!</span>
<span class="w">      </spa