The 'hpcdtoppm' code in this directory is just a dummy version of the program
that tells you where to get the real code.

The real "hpcdtoppm' source code cannot be distributed on Sourceforge because
a copyright holder does not license it in a way open enough to meet
Sourceforge's requirements.

Therefore, the Netpbm maintainer distributes 'hpcdtoppm' via another channel
and distributes this dummy directory in the main Netpbm source tree on
Sourceforge.

The code is at 

  http://ibiblio.org/pub/Linux/apps/graphics/convert/hpcdtoppm-netpbm.tgz

When you get the real 'hpcdtoppm' tarball, just unpack its contents into the
'hpcdtoppm-import' subdirectory.  Then build Netpbm normally.  The build
detects the presence of the code and builds and packages the real 'hpcdtoppm'
program instead of the dummy one.

Bear in mind when you get the real 'hpcdtoppm' that it is not as openly
licensed as what's in the rest of the Netpbm source tree.  As you'll see in
the license that comes with 'hpcdtoppm', you may _not_ sell it to someone
else.)