R> From: "Rich" 

 R> As a follow on, what is the feature or property of the OS
 R> that you believe is responsible and should not exist in
 R> order to prevent any programmers from making mistakes with
 R> shared libraries that introduce compatibility problems?
 R> Please answer this for both OS/400 and Windows and any
 R> other systems with which you have familiarity that also
 R> have this problem like Linux.

FWIW: linux systems can carry multiple versions of the same libraries at
the same time so that programs that need to use them may do so... the
ability of a system having this is directly related to the method of
installing the updates... instead of replacing or upgrading, just
install... many/most things end up in their own directories that carry the
version number of the install and then a link is created using a common
name that points to the proper directory... in some cases, one must
recompile apps to use the original name instead of the link to locate their
needed libraries...

all i'm saying is that it is possible and easily done... whether someone
has the ability or knowledge to do so is another matter altogether...

as an example, i have a linux box with several different kernels on it...
each one has it's own /lib/modules directory where modules are located that
are specific to each kernel... this is due to some structure changes in the
kernel... my system flips between kernel versions very easily and there is
nothing copied or altered... i simpy tell it to use vmlinuz-2.2.19-63 or
vmlinuz-2.2.19.64 or whatever and everything else is already in place...

)\/(ark