r of components or indices in a pixel,
                        <math overflow="scroll"><mi mathvariant="italic">l</mi></math>
                        is the number of pixels in a row
                        (<code class="constant">GL_UNPACK_ROW_LENGTH</code> if it is greater than 0,
                        the
                        <math overflow="scroll"><mi mathvariant="italic">width</mi></math>
                        argument to the pixel routine otherwise),
                        <math overflow="scr