At the place where I am working now, we use a software tool
(for comparing data files) called  "Beyond Compare"
[version 2.0.2 (build 180)].
It comes with an "About" screen that says
<< Copyright (c) 1996-2003 Scooter Software
     All rights reserved
     www.scootersoftware.com >>
and the "credits" list a bunch of other co.'s that presumably contributed in
some way (or, - could it be? - maybe they sold [licensed?] the rights
(or should I be saying "conveyed"?  I'm not up on the latest!!)
on condition that the user / reseller [Scooter Software] would list
them in the credits?)
and some of them [credits] come with hyper links to various URLs,
but some of the links are broken (403), (e.g.) and one that I "did" find
that still worked, was in 'auf Deutsch'.  (German) [as in, ".de"]
    One of the things I found interesting about this, and the reason why I
got the idea to mention it here, is the fact that, right at the beginning of
their on-line help, they have 2 links, to
Sample uses of Beyond Compare
What Beyond Compare DOESN'T Do
and I did not spend much time checking the "Sample uses of Beyond Compare".
[...SNIP... boring stuff...] my main comment is not about that.
    My main comment is about: the list of
     **!!** ----->> "What Beyond Compare DOESN'T Do".  <<-----  **!!**
Check this:  [begin quote:]
What Beyond Compare DOESN'T Do
Beyond Compare cannot compare MS Word, MS Excel or Adobe PDF documents
side-by-side. These have complex, proprietary formats that BC doesn't
understand. However, if you first save documents as text files, BC can
compare their contents.
Beyond Compare does not run on a Mac, at least not natively. Users
have reported some success running BC under VirtualPC. For OS/2 fans,
BC can be relinked using Odin, with few problems. We do not currently
have a Unix version of BC, although we have plans to develop a Linux
version.
Beyond Compare does not do 3-way compares, or automated source code merging.
[: end quote].
BOTTOM LINE:
Another good argument (IMHO), for avoiding
    "secret / vendor-lock-in" proprietary formats!
PS:  I remembered to change my "mode switch" to "Plain Text"
    before sending this message, but if anyone wants to see
    the original version that I typed, as an ".rtf" file
    (circa 3K bytes),   it is available.
    (maybe rtf was "once" a mysterious format, but
     by today's standards, it is far from being a
     "secret / vendor-lock-in" proprietary format.)
   (in fact, according to
       http://en.wikipedia.org/wiki/Rich_Text_Format
    it says that RTF "is a proprietary document file format",
    but then it also says: "Most word processors are able
    to read and write RTF documents.")
   (so no co. is going to be able to hold your data
     hostage now, if some of it is "in" that "format").
In fact, I tried to "attach" it (that .rtf file)
as an attachment to this PLUG-Discuss e-mail message.
I am not sure whether that worked (does the list server
support that?)  but if not, then just let me know
if you want to see  the ".rtf" file,
(circa 3K bytes!:)
and I can probably just go to my "SENT Items" folder,
and forward you the copy
[er, um original] with the ".rtf" file as an attachment.
-- 
Mike Schwartz
Glendale  AZ
schwartz@acm.org