P are extensions to the DEFLATE format
  and are implemented as subclasses
  of <a href='#deflate-compressor'><tt>DEFLATE-COMPRESSOR</tt></a>
  with a few methods implemented for the protocol.

<p>Salza2 is the successor
to <a href="http://cliki.net/Salza">Salza</a>, but it is not
backwards-compatible. Among other changes, Salza2 drops support for
compressing Lisp character data, since the compression formats are
octet-based and obtaining encoded octets from Lisp characters varies
from implementation to imp