A Forward Sequence is a <ahref="./Sequence.html">Sequence</a> which guarantees that its elements are arranged in a definite order, and that the ordering will not change spontaneously [<ahref="#1">1</a>]. Iterators into a forward sequence satisfy the <ahref="./Forward_Iterator.html">Forward Iterator</a> requirements.
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<h3>Refinement of</h3>
<p>
<ahref="./Sequence.html">Sequence</a>
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<h3>Valid expressions</h3>
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Forward Sequence does not define any new expressions beyond those defined in <ahref="./Sequence.html">Sequence</a>. However, it refines the expression requirements.
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<tableborder="1">
<tr><th> Expression </th><th> Expression type </th></tr>
<tr><td><code>typename begin<s>::type</code></td><td>A model of <ahref="./Forward_Iterator.html">Forward Iterator</a></td></tr>
<tr><td><code>typename end<s>::type</code></td><td>A model of <ahref="./Forward_Iterator.html">Forward Iterator</a></td></tr>
</table>
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<h3>Invariants</h3>
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For any forward sequence <code>s</code> the following invariants always hold:
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<li>Two different iterations through <code>s</code> will access its elements in the same order.