    <dt>(base - count lines)</dt>
    
      <dd>Adjust the index backward by <code>count</code> lines, retaining the same character position within the line. If there are fewer than <code>count</code> lines before the line containing the current index, then set the index to refer to the same character position on the first line of the text. Then, if the line is not long enough to contain a character at the indicated character position, adjust the character position to refer to the last character of the lin