hed onto such a chain must at least be <A HREF="../concepts/input_filter.html">InputFilters</A>. Any <A HREF="../concepts/device.html">Device</A> pushed onto such a chain must at least be a <A HREF="../concepts/source.html">Source</A>.
</P>
<P>
    Chains are <A HREF='../../../../doc/html/CopyConstructible.html' TARGET='_top'>CopyConstructible</A> and <A HREF='../../../../doc/html/Assignable.html' TARGET='_top'>Assignable</A>. A copy of a chain represents the same sequence of Filters and Devices as the orig