Issue: PACKAGE-CLUTTER (Version 5)

[Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>]

    ....
      A valid implimentation may have or put additional properties
      on symbols (even user created symbols) as long as the
      property indicators are not in the LISP, KEYWORD or USER
      package.
    ....

The wording should be stronger. I think it should say that it will not
use any property names which are on any user-created packages (except by
inheritance). In other words, it should say that the only permissible
packages of symbols which may be used by the system for properties are
those which are initially allocated by the system for its own use (or
allocated later under some known contract between the system and user if
any implementations ever do this).

Also, SETF of GET, GETF(?), and SYMBOL-PLIST need to be explicitly excepted
for the obvious reason that they are requests by the user for the system
to violate the rules we're describing above.