In this section, we perform a textual diff on the S and the W licenses to discuss these differences and their ramifications.
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
CERN Open Hardware Licence Version 2 - Strongly Reciprocal Preamble CERN has developed this licence to promote collaboration among hardware designers and to provide a legal tool which supports the freedom to use, study, modify, share and distribute hardware designs and products based on those designs. Version 2 of the CERN Open Hardware Licence comes in three variants: CERN-OHL-P (permissive); and two reciprocal licences: CERN-OHL-W (weakly reciprocal) and this licence, CERN-OHL-S (strongly reciprocal). |
CERN Open Hardware Licence Version 2 - Weakly Reciprocal Preamble CERN has developed this licence to promote collaboration among hardware designers and to provide a legal tool which supports the freedom to use, study, modify, share and distribute hardware designs and products based on those designs. Version 2 of the CERN Open Hardware Licence comes in three variants: CERN-OHL-P (permissive); and two reciprocal licences: this licence, CERN- OHL-W (weakly reciprocal) and CERN-OHL-S (strongly reciprocal). |
You can see that the S license is compatible with itself. The W license is compatible with both W and S.
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
1 Definitions 1.1 'Licence' means this CERN-OHL-S. 1.2 'Compatible Licence' means a) any earlier version of the CERN Open Hardware licence, or b) any version of the CERN-OHL-S, or c) any licence which permits You to treat the Source to which it applies as licensed under CERN-OHL-S provided that on Conveyance of any such Source, or any associated Product You treat the Source in question as being licensed under CERN-OHL-S. |
1 Definitions 1.1 'Licence' means this CERN-OHL-W. 1.2 'Compatible Licence' means a) any earlier version of the CERN Open Hardware licence, or b) any version of the CERN-OHL-S or the CERN-OHL-W, or c) any licence which permits You to treat the Source to which it applies as licensed under CERN-OHL-S or CERN-OHL-W provided that on Conveyance of any such Source, or any associated Product You treat the Source in question as being licensed under CERN-OHL-S or CERN-OHL-W as appropriate. |
Now we start with the very interesting concept of an Available Component. The definition in both licenses are almost the same but not completely. The difference is subtle, but clause 1.7 b) i) has to be a physical part for S, whereas for W it can also be a library or code.
Firstly, an available component can be a part, sub-assemlby, library or code. For the S license, if it is a library or code, then it has to be licensed to you under a compatible license (clause a)) or it has to be part of the normal distribution of a tool used to design or make the product (clause b) ii)).
If it is not a library or code, so it is a part or sub-assembly, then you can declare it to be an available component if it is a physical part together with all the rights, information and source code to make it or source it.
So, as an example, if you license your hardware with S, it can make use of some proprietary controller that requires proprietary firmware to run it on the condition that this controller and the firmware is available to you and other licensees. This would then be an available component.
For the W license, it is not necessary that this is a physical part; it can be a library or code as well. Suppose your design requires a proprietary software package, that is generally available to anyone, you can license your design under the W license, but not under the S license.
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
1.7 'Available Component' means any part, sub-assembly, library or
code which:
a) is licensed to You as Complete Source under a Compatible
Licence; or
b) is available, at the time a Product or the Source containing
it is first Conveyed, to You and any other prospective
licensees
i) as a physical part with sufficient rights and
information (including any configuration and
programming files and information about its
characteristics and interfaces) to enable it either to
be Made itself, or to be sourced and used to Make the
Product; or
ii) as part of the normal distribution of a tool used to
design or Make the Product.
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1.7 'Available Component' means any part, sub-assembly, library or
code which:
a) is licensed to You as Complete Source under a Compatible
Licence; or
b) is available, at the time a Product or the Source containing
it is first Conveyed, to You and any other prospective
licensees
i) with sufficient rights and information (including any
configuration and programming files and information
about its characteristics and interfaces) to enable it
either to be Made itself, or to be sourced and used to
Make the Product; or
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ii) as part of the normal distribution of a tool used to
design or Make the Product.
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The W license has an extra definition called External Material. This is interesting because it isn’t completely clear how this is different from available components since there is no limitation on an available component to be physical as in the S license. Most likely the difference is in the fact that for external material, it requires a well-defined interface. We expect to see the difference below.
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
1.8 'Complete Source' means the set of all Source necessary to Make ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- a Product, in the preferred form for making modifications, including necessary installation and interfacing information both for the Product, and for any included Available Components. |
1.8 'External Material' means anything (including Source) which: a) is only combined with Covered Source in such a way that it interfaces with the Covered Source using a documented interface which is described in the Covered Source; and b) is not a derivative of or contains Covered Source, or, if it is, it is solely to the extent necessary to facilitate such interfacing. 1.9 'Complete Source' means the set of all Source necessary to Make a Product, in the preferred form for making modifications, including necessary installation and interfacing information both for the Product, and for any included Available Components. |
In the clauses below an interesting distinction in the level of reciprocity: For the S license there is an extra clause that defines that including the covered source in a larger work means a modification of the covered source and that this larger work is then the modified covered source. Clause 3.3 (shown in the next subsection) states that the modified covered source should retain all notices and the license of the covered source (so the S or the W).
In other words, work licensed under W can be used in larger works without having an effect on the license of the larger work, so it can be proprietary as well. For S this larger work has to have the S license. So, both licenses are reciprocal but indeed, S is much stronger.
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
3 Copying, modifying and Conveying Covered Source
3.1 You may copy and Convey verbatim copies of Covered Source, in
any medium, provided You retain all Notices.
3.2 You may modify Covered Source, other than Notices, provided that
You irrevocably undertake to make that modified Covered Source
available from a Source Location should You Convey a Product in
circumstances where the recipient does not otherwise receive a
copy of the modified Covered Source. In each case subsection 3.3
shall apply.
You may only delete Notices if they are no longer applicable to
the corresponding Covered Source as modified by You and You may
add additional Notices applicable to Your modifications.
Including Covered Source in a larger work is modifying the
Covered Source, and the larger work becomes modified Covered
Source.
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3 Copying, modifying and Conveying Covered Source
3.1 You may copy and Convey verbatim copies of Covered Source, in
any medium, provided You retain all Notices.
3.2 You may modify Covered Source, other than Notices, provided that
You irrevocably undertake to make that modified Covered Source
available from a Source Location should You Convey a Product in
circumstances where the recipient does not otherwise receive a
copy of the modified Covered Source. In each case subsection 3.3
shall apply.
You may only delete Notices if they are no longer applicable to
the corresponding Covered Source as modified by You and You may
add additional Notices applicable to Your modifications.
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We clearly see in this section that Available Components have their own license in both S and W. In the W license the same is true for External Material but again, here it reiterated that the work is interfaced to the external material
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
3.3 You may Convey modified Covered Source (with the effect that You
shall also become a Licensor) provided that You:
a) retain Notices as required in subsection 3.2;
b) add a Notice to the modified Covered Source stating that You
have modified it, with the date and brief description of how
You have modified it;
c) add a Source Location Notice for the modified Covered Source
if You Convey in circumstances where the recipient does not
otherwise receive a copy of the modified Covered Source; and
d) license the modified Covered Source under the terms and
conditions of this Licence (or, as set out in subsection
8.3, a later version, if permitted by the licence of the
original Covered Source). Such modified Covered Source must
be licensed as a whole, but excluding Available Components
contained in it, which remain licensed under their own
applicable licences.
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3.3 You may Convey modified Covered Source (with the effect that You
shall also become a Licensor) provided that You:
a) retain Notices as required in subsection 3.2;
b) add a Notice to the modified Covered Source stating that You
have modified it, with the date and brief description of how
You have modified it;
c) add a Source Location Notice for the modified Covered Source
if You Convey in circumstances where the recipient does not
otherwise receive a copy of the modified Covered Source; and
d) license the modified Covered Source under the terms and
conditions of this Licence (or, as set out in subsection
8.3, a later version, if permitted by the licence of the
original Covered Source). Such modified Covered Source must
be licensed as a whole, but excluding Available Components
contained in it or External Material to which it is
interfaced, which remain licensed under their own applicable
licences.
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Clause 4 in S is the same as clause 4.1 in W. When a Product is made or conveyed, the recipients should have a copy of the Complete Source which is the Covered Source. The Available Components keep there own licenses. The W license adds clause 4.2 that states that the source of External Material does not need to included. This seems to imply that the source of Available Components needs to be included, but clause 1.8 states that the source of Available Components does not need to be included provided that there is enough information to make or source it. Apparently there is a subtle difference that hopefully arises in the use-cases.
The W license also adds clause 4.3 that states that the Product itself may have a different license.
| CERN-OHL-S-2.0 | CERN-OHL-W-2.0 |
|---|---|
4 Making and Conveying Products You may Make Products, and/or Convey them, provided that You either provide each recipient with a copy of the Complete Source or ensure that each recipient is notified of the Source Location of the Complete Source. That Complete Source is Covered Source, and You must accordingly satisfy Your obligations set out in subsection 3.3. If specified in a Notice, the Product must visibly and securely display the Source Location on it or its packaging or documentation in the manner specified in that Notice. ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- ---------------------------------------------------------------------- |
4 Making and Conveying Products 4.1 You may Make Products, and/or Convey them, provided that You either provide each recipient with a copy of the Complete Source or ensure that each recipient is notified of the Source Location of the Complete Source. That Complete Source includes Covered Source and You must accordingly satisfy Your obligations set out in subsection 3.3. If specified in a Notice, the Product must visibly and securely display the Source Location on it or its packaging or documentation in the manner specified in that Notice. 4.2 Where You Convey a Product which incorporates External Material, the Complete Source for that Product which You are required to provide under subsection 4.1 need not include any Source for the External Material. 4.3 You may license Products under terms of Your choice, provided that such terms do not restrict or attempt to restrict any recipients' rights under this Licence to the Covered Source. |