o a single sequence of characters, with a single repositionable read/write head. 
</UL>

<A NAME="filter_concepts"></A>
<H2>Filter Concepts</H2>

<P>The most important Filter concepts are these:</P>

<UL>
    <LI><A STYLE="font-weight:normal" HREF="../concepts/filter.html">Filter:</A> Base for all Filter concepts, provides associated character type and category.
    <LI><A HREF="../concepts/input_filter.html">InputFilter:</A> Filters characters read from a Source.
    <LI><A HREF="../concepts/output_filter.