internal symbol preservation

[David.Dill@A.CS.CMU.EDU (C410DD60)]

"::"  should be regarded as a convenience feature of the programming
environment, and should not be used in programs.  Internal symbols are
internal because they are not supposed to be accessed from outside of
the package.  The obvious right thing is that a common lisp
implementation should not feel obliged to keep internal symbols around
just so they can be accessed from outside of the package.  Early drafts
of the package chapter said this, but apparently this was changed as
one of many unimprovements.