"parameter"><code>P</code></em> is used as
            <math overflow="scroll"><msub><mi>D</mi><mi>sub</mi></msub></math> and the
            array layer is specified in the second to last component of <em class="parameter"><code>P</code></em>. (The second component of <em class="parameter"><code>P</code></em>
            is unused for <span class="emphasis"><em>1D</em></span> shadow lookups.)
        </p>
        <p>
            For non-shadow variants, the array layer comes from the last component of <em 