This is a very basic, two-image slide show, consisting of a pair of grayscale or truecolor PNG images (note the absence of PLTE chunks, so they cannot be colormapped images) and nothing else. In fact, the MNG stream is a little too basic; it contains no color space information, so the images will not display the same way on different platforms. It includes no explicit timing information, so the decoder will display the images at a rate of one frame per tick. At the minimum value of MHDR's ticks-per-second field, that translates to a duration of just one second for the first image and one or more seconds for the second image (in practice, probably indefinitely). There is no way to use this abbreviated method to define a duration longer than one second. To avoid those problems, sRGB and FRAM chunks could be added after MHDR; the latter would specify an interframe delay--say, five seconds' worth. Thus the simplest reasonable MNG looks like Figure 12-2.