GL_SGIS_texture_lod
https://www.khronos.org/registry/OpenGL/extensions/SGIS/SGIS_texture_lod.txt
GL_SGIS_texture_lod

	GL_TEXTURE_MIN_LOD_SGIS 0x813A
	GL_TEXTURE_MAX_LOD_SGIS 0x813B
	GL_TEXTURE_BASE_LEVEL_SGIS 0x813C
	GL_TEXTURE_MAX_LEVEL_SGIS 0x813D
