able:</A> A source which allows characters to be put back to the input sequence.
    <LI><A HREF="../concepts/pipable.html">Pipable:</A> A Filter which can appear in <A HREF="pipelines.html">pipelines</A>.
</UL>

<A NAME="convenience"></A>
<H2>Convenience Templates and <CODE>typedef</CODE>s</H2>

<P>
    The Iostreams library provides several templates intended for derivation by user-defined Filter and Device types. They ease the task of defining Filters and Devices by providing member types and default imp