NOTE(m): Copied from https://github.com/svanderburg/libilbm/blob/master/doc/additions/PBM.asc

Apparently, The PC version of Deluxe Paint stores images in a slightly different
format compared to the Amiga version of the Deluxe Paint. After doing some
experiments, I have discovered the following differences:

- The IFF form type used is: 'PBM ' instead of 'ILBM'.

- As PC hardware does not know anything about bitplanes, its BODY uses chunky
  format, in which every byte represents a pixel.

- Interleaving scanlines is to smoothly render planar graphics data on an Amiga,
  so that no visual corruption is visible while calculating the index values of
  each pixel. On the PC this is not necessary, so we don't have to interleave or
  deinterleave anything.

- Some Amiga specific chunks, such as CAMG are not used.

Sander van der Burg