GL_NV_conservative_raster
http://www.opengl.org/registry/specs/NV/conservative_raster.txt
GL_NV_conservative_raster
	GL_CONSERVATIVE_RASTERIZATION_NV 0x9346
	GL_SUBPIXEL_PRECISION_BIAS_X_BITS_NV 0x9347
	GL_SUBPIXEL_PRECISION_BIAS_Y_BITS_NV 0x9348
	GL_MAX_SUBPIXEL_PRECISION_BIAS_BITS_NV 0x9349
	void glSubpixelPrecisionBiasNV (GLuint xbits, GLuint ybits)
