e accepted:
                    <code class="constant">GL_KEEP</code>,
                    <code class="constant">GL_ZERO</code>,
                    <code class="constant">GL_REPLACE</code>,
                    <code class="constant">GL_INCR</code>,
                    <code class="constant">GL_INCR_WRAP</code>,
                    <code class="constant">GL_DECR</code>,
                    <code class="constant">GL_DECR_WRAP</code>, and
                    <code class="constant">GL_INVERT</code>. The initi