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Re: opencascade license in squeeze

On Fri, 05 Mar 2010 20:09:45 -0500 Adam C Powell IV wrote:

> Hi Francesco,


> I contacted upstream a number of times a couple of years ago, and never
> got any reply.

Please try again, the company seems to have been more responsive in
recent times.
As I said, I successfully used their contact web form:
and then began talking with an employee directly via e-mail.

> That said, a couple of people convinced me that OCTPL is (now)
> GPL-compatible, so FreeCAD is distributable, based on the following
> points:
>       * The clause indicating "You are also obliged to send your
>         modifications of the original source code (if you've made any)
>         to the Initial Developer", which was in OCTPL 6.2, is gone from
>         OCTPL 6.3.0.  The license on opencascade.org is wrong, see the
>         LICENSE file in the distribution, where the introductory
>         language containing the above clause has been removed.

I hadn't noticed that the license file included in the actual software
package differs from what can be read on the web site.
Thanks for pointing this out!

Dropping the introductory preamble is really an improvement, as it
helps reducing the interpretation uncertainty.

>       * The statement that the copyright license is not a trademark
>         license is not in conflict with the GPL, and explicitly stated
>         as an option in GPL-3.  I don't think anyone believes GPL-3 is
>         incompatible with GPL-2...

As it has already been pointed out by Charles Plessy, the GNU GPL v3 is
indeed incompatible with the GNU GPL v2.
But anyway, I don't think the OCTPL trademark clause (OCTPL v6.3,
Section 10.) is the cause of its GPL-incompatibility.

>       * There are other copyleft licenses which are GPL-compatible but
>         do not include explicit GPL-compatibility clauses.  (And there
>         are probably copyleft licenses which claim to be GPL-compatible
>         in their clauses but aren't.)  The basic requirement is that the
>         license not add additional restrictions beyond the GPL.

In order for the OCTPL to be GPL-compatible, it must be legally
possible to combine a GPL'ed work and an OCTPL'ed work into a new work,
while complying with both licenses at the same time.

The GNU GPL insists that the whole new work must be available under the
terms of the GNU GPL itself and that no further restrictions may be

Hence, the OCTPL must not include any restriction beyond the ones found
in the GNU GPL (apart from a limited set, listed in Section 7., as far
as the GNU GPL v3 is concerned).

I think the OCTPL includes some GPL-incompatible restrictions.
Quoting from the license text:

| Open CASCADE Technology Public License
| License version : 6.3 August, 2008
| Please read this license carefully and completely before downloading
| this software. By downloading, using, modifying, distributing and
| sublicensing this software, you indicate your acceptance to be bound
| by the terms and conditions of this license. If you do not want to
| accept or cannot accept for any reasons the terms and conditions of
| this license, please do not download or use in any manner this
| software.

This clause makes the license legally binding even to people
who merely use or download the software (sections 2, 3, and 13 restate
the same concept).
This, even though it seems to be allowed by copyright laws
(at least in some jurisdictions, see
is not usually found in Free Software licenses.

This is a restriction (being compelled to accept license terms in order
to merely use the software) that is not found in the GNU GPL (v2 or v3).
I think it makes the OCTPL GPL-incompatible.

| 7. Additional terms
| You may choose to offer, on a non-exclusive basis, and to charge a fee
| for any warranty, support, maintenance, liability obligations or other
| rights consistent with the scope of this License with respect to the
| Software (the "Additional Terms") to the recipients of the Software.
| However, You may do so only on Your own behalf and on Your sole and
| exclusive responsibility. You must obtain the recipient's agreement
| that any such Additional Terms are offered by You alone, and You
| hereby agree to indemnify, defend and hold the Initial Developer and
| any Contributor harmless for any liability incurred by or claims
| asserted against the Initial Developer or any Contributors with
| respect to any such Additional Terms.

The indemnification clause is something that may be problematic,
however it seems to hold only for people who offer "Additional Terms".
This does not look like a DFSG-freeness issue.

However, the GNU GPL v2 allows people to offer "warrany protection
in exchange for a fee" (see GPLv2, Section 1.) without imposing any
indemnification obligation.  Hence this is a restriction not found
in the GNU GPL v2.
I think this makes the OCTPL incompatible with the GNU GPL v2.

The GNU GPL v3, on the other hand, seems to allow the addition of
this non-permissive term (see GPLv3, Clause 7f).

| 5. Your license
| You hereby grant all Contributors and anyone who becomes a party under
| this License a world-wide, non-exclusive, royalty-free and irrevocable
| license under the Applicable Intellectual Property Rights owned or
| controlled by You, to use, reproduce, modify, distribute and
| sublicense all Your Modifications under the terms and conditions of
| this License.

This is a copyleft clause.

If the OCTPL is more permissive than the GNU GPL in some regard
(I think it is), then I am forced by the OCTPL to grant on my
Modifications more permissions than the ones found in the GNU GPL.
Being compelled to grant more permissions than the ones found in the
GNU GPL, is a restriction not found in the GNU GPL.
This is possibly another reason why the OCTPL is GPL-incompatible.

> [As a result of not being subscribed, please CC me in replies.]


 Need some pdebuild hook scripts?
..................................................... Francesco Poli .
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