Copyleft-Policy.txt

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% Annex to the OSADL Open Source Policy Template
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% Copyright (c) 2019,2020 Open Source Automation Development Lab (OSADL) eG
% Author: Carsten Emde, Caren Kresse
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Copyleft policy

This document lists FOSS licenses that we consider to have a copyleft clause.
The extend of the copyleft clause is categorized as "strong" (i.e. any
derivative work is affected) or "weak" (i.e. separable linked components are not
affected). Section 2 describes how we handle the use of copyleft licenses in our
products.
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After review, this list of copyleft licenses may instead be included in the ->
"List of known licenses".
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1 Copyleft licenses

The vast majority of licenses clearly state whether they contain a so-called
copyleft clause (for explanations see -> "What is copyleft?"). It is generally
agreed that this is the case for the licenses given in table Table 1. In
addition to the name of the license, the SPDX Identifier and the extend of the
copyleft is given. The latter may be "strong", requiring that the original
license must always be used, or "weak", indicating that linked, but separable
libraries may be licensed under a license of choice.

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Interpretations of the extend of strong copyleft clauses are heterogeneous. This
policy should therefore reflect the company's individual interpretation. The
Supplement -> "What is a derivative work?" gives guidelines for such an
interpretation.
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License name (SPDX Identifier): Scope of copyleft

GNU Affero General Public License v3.0 (AGPL-3.0): Strong
Common Development and Distribution License 1.0 (CDDL-1.0): Weak
Common Public License 1.0 (CPL-1.0): Strong
Eclipse Public License 1.0 (EPL-1.0): Strong
Eclipse Public License 2.0 (EPL-2.0): Weak
European Union Public License 1.1 (EUPL-1.1): Strong
GNU General Public Liense v2.0 (GPL-2.0): Strong
GNU General Public Liense v3.0 (GPL-3.0): Strong
IBM Public License Version 1.0 (IPL-1.0): Strong
GNU Lesser General Public License v2.1 (LGPL-2.1): Weak
GNU Lesser General Public License v3.0 (LGPL-3.0): Weak
Mozilla Public License 1.1 (MPL-1.1): Weak
Mozilla Public License 2.0 (MPL-2.0): Weak
Microsoft Reciprocal License (MS-RL): Strong
Open Software License 3.0 (OSL-3.0): Strong
Reciprocal Public License 1.5 (RPL-1.5): Weak

Table 1: Copyleft licenses

Questionable copyleft
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Unfortunately, some licenses are less clear with respect to their copyleft
status, since there are good arguments for various views. If software that is
licensed under such licenses, is going to be included in a product and
distributed along with it, a decision must be made on how to handle these
licenses. Table 2 lists the three most popular licenses with an unclear copyleft
status. For possible interpretations see -> "OSADL Open Source License
Obligations Checklists".
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License name (SPDX Identifier): Scope of copyleft

Boost Software License 1.0 (BSL-1.0):
Option 1: Strong
Option 2: Weak
Option 3: None

Microsoft Public License (MS-PL):
Option 1: Strong
Option 2: Weak
Option 3: None

OpenSSL License (OpenSSL-1.0):
Option 1: Strong
Option 2: Weak
Option 3: None

Table 2: Licenses with an unclear copyleft status

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Table 1 may need to be extended if one or more of the licenses listed in Table 2
are considered to be copyleft licenses.
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2 Using copyleft licenses in our products

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Since many standard libraries are licensed under a copyleft license, it may
appear impossible or at least very difficult to abandon copyleft licenses
altogether. However, some management may decide to do so and, in consequence,
this topic should be discussed and decided upon.
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Option 1: As a general rule, FOSS that is licensed under a copyleft license may
not be used in our products.
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Option 2: There is no general restriction on the use of FOSS that is licensed
under a copyleft license. However, individual projects may define per-project
rules on combining FOSS under copyleft licenses with proprietary software of our
company.
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This is appropriately noted in the lower part of the -> "Compatibility Matrix"
that is an Annex to this FOSS policy.