index HEAD target         working index HEAD
----------------------------------------------------
 X       U     A    A     --soft  (disallowed)
                          --mixed  X       A     A
                          --hard   A       A     A
                          --merge  A       A     A
                          --keep  (disallowed)</pre>
</div>
</div>
<div class="paragraph">
<p><code>X</code> means any state and <code>U</code> means an unmerged index.</p>
</div>
</div>
</div>
<div class="sect1">
