Issue: PATHNAME-SUBDIRECTORY-LIST (Version 2)

[gz@spt.entity.com (Gail Zacharias)]

   Date: Fri, 8 Jul 88 10:21:40 PDT
   From: Jim McDonald <edsel!jlm@labrea.stanford.edu>
   >                         I think :UP might just be a keyword, since I can't
   >  imagine there being more than one way of moving up.  
   ...
   Then using csh, after cd /foo/b1/b2/.., pwd will show /foo/a1/a2,
    but using bsh, after cd /foo/b1/b2/.., pwd will show /foo/b1.

Right you are.  Of course Unix doesn't have any syntax which would allow the
pathname itself to specify which variant it wants, but some other system
might.  So this does show that it would be unwise to assume that every
implementation would be able to represent all upward motion in pathnames with
a single token such as :UP.