#note_1"><SUP>[1]</SUP></A>
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<P>
    In general, a Filter or Device may provide access to an <SPAN>input sequence</SPAN>, for reading, an <SPAN>output sequence</SPAN>, for writing, or both. The relationship between the two sequences, as well as the operations that may be performed on them, depends on the Filter or Device type. The various possible relationships between input and output are referred to as <A HREF="modes.html">modes</A>.<SUP><A CLASS="footnote_ref" NAME="note_2_ref" HREF="#note_2">[2]</A>