According to README.txt:

   Debian is available for various kinds of computers ("architectures"),
   like "IBM-compatible" PCs (i386), Compaq's Alpha, Sun's Sparc,
   Motorola/IBM's PowerPC, and (Strong)ARM processors. Check the ports
   page for more information.

This omits amd64, and includes several unsupported architectures and
obsolete company names.  (In fact it doesn't seem to match the list of
supported architectures at any point in time, though it was almost
correct around 2001-2002.)

Ben.