A Bidirectional Sequence is a <ahref="./Forward_Sequence.html">Forward Sequence</a>, which provides iterators that satisfy the <ahref="./Bidirectional_Iterator.html">Bidirectional Iterator</a> requirements.
Bidirectional Sequence does not define any new expressions beyond those defined in <ahref="./Forward_Sequence.html">Forward Sequence</a>. However, it refines the expression requirements.
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<tr><th> Expression </th><th> Expression type </th></tr>
<tr><td><code>typename begin<s>::type</code></td><td>A model of <ahref="./Bidirectional_Iterator.html">Bidirectional Iterator</a></td></tr>
<tr><td><code>typename end<s>::type</code></td><td>A model of <ahref="./Bidirectional_Iterator.html">Bidirectional Iterator</a></td></tr>