Releasing under a different liberal license?

[Miriam Ruiz <miriam@debian.org>]

Hi,

There's some old code I am working on, but which unfortunately is not
supported by upstream anymore. Thus, I've decided to become the new
upstream and make the code evolve myself. The original license says
hat:

   Permission to use, copy, and distribute this software and its
   documentation for any purpose with or without fee is hereby granted,
   provided that the above copyright notice appear in all copies.

   Permission to distribute binaries including jfs-files for any purpose
   is hereby granted.

   This software is provided "as is" without express or implied warranty.

Some time ago, I wrote to the original upstream asking for
clarification of the license:

> Hi,
>
> I'm interested in your program JFS2, even though it is
> unmaintained now. I just have a doubt regarding the
> license of the program:
>
>   Permission to use, copy, and distribute this
> software and its
>   documentation for any purpose with or without fee
> is hereby granted,
>   provided that the above copyright notice appear in
> all copies.
>
>   Permission to distribute binaries including
> jfs-files for any purpose
>   is hereby granted.
>
>   This software is provided "as is" without express
> or implied warranty.
>
> Does the license include permission to modify the code
> and redistribute the modified program?
>
> Also, does this license covers the contents of
> jfsdoc204.tar.gz too?
>
> Thanks in advance,
> Miry

And I received a very clarifying answer:

> Hi,
>
> Regarding the license of JFS2.
>
> The intension with the license was: you can use the program and its
> documentation any way you want, as long as you don't try to take control
> over (copyright) the program (I should y have releases it under a
> GNU-lincense). So the answer to your questions is:
>
> > Does the license include permission to modify the code
> > and redistribute the modified program?
>
> Yes. You are welcome to modify the code and redistribute the modified code.
>
> > Also, does this license covers the contents of
> > jfsdoc204.tar.gz too?
>
> Yes. You can use the documentation any way you want.
>
> Best regards
> Jan

Upstream seems not to be reachable anymore, the original web site has
disappeared ( http://inet.uni2.dk/~jemor/jfs.htm ) and I think that
his email address at that domain might be too. I have been evolving
and cleaning the code for a couple of weeks (
http://repo.or.cz/w/jfs-fuzzy.git ), but I'd like to release my
version with a more standard license (I'm thinking about BSD-2 or MIT)
before uploading the package to Debian.

My question is then, can I release my derivative version of the
software under a BSD-2 or MIT license (respecting the original
copyright statements, of course)?

Lots of thanks,
Miry