CE12</code>,
                    <code class="constant">GLU_LUMINANCE16</code>,
                    <code class="constant">GLU_LUMINANCE_ALPHA</code>,
                    <code class="constant">GLU_LUMINANCE4_ALPHA4</code>,
                    <code class="constant">GLU_LUMINANCE6_ALPHA2</code>,
                    <code class="constant">GLU_LUMINANCE8_ALPHA8</code>,
                    <code class="constant">GLU_LUMINANCE12_ALPHA4</code>,
                    <code class="constant">GLU_LUMINANCE12_ALPHA12</