<li>GL_ARB_depth_clamp (supported in Intel i965 DRI and software drivers)</li>
<li>GL_NV_depth_clamp (supported in Intel i965 DRI and software drivers)</li>
<li>GL_ARB_provoking_vertex (same as GL_EXT_provoking_vertex)</li>
<li>GL_ARB_depth_clamp (supported in Intel i965 DRI and software drivers)</li>
<li>GL_NV_depth_clamp (supported in Intel i965 DRI and software drivers)</li>
<li>GL_ARB_provoking_vertex (same as GL_EXT_provoking_vertex)</li>