Policy for copyright statement in ODL

[aringh]

As pointed out in #1377, just as we have guidelines for how to write commit messages (#4), how to document the code (#279, #854), and how to write error messages (#446), we should also have a policy for how to maintain a proper copyright statement in the code.

• How does the copyright statement we use look like?
• Which code should include the statement?
• What is our policy for updating a potential year given in the statement?

[kohr-h]

How does the copyright statement we use look like?

By default, use the short header as in any of our source files:

# Copyright 2014-2018 The ODL contributors
#
# This file is part of ODL.
#
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/.

If the code loads some external resource, e.g., a dataset, the license of that resource should be mentioned as well. Example:

# The dataset is subject to the terms of the
# Creative Commons Attribution 4.0 International License.
#
# You should have received a copy of the license along with this
# work. If not, see https://creativecommons.org/licenses/by/4.0/.

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Which code should include the statement?

All files except examples. Likely, they're covered anyway, but we want to avoid the boilerplate lines.

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What is our policy for updating a potential year given in the statement?

I think we have settled for on-demand, i.e., when modifying a file with an outdated year range. As I pointed out in the discussion in #1377, what seems to matter is that the last revision is covered by the range, so if a file hasn't been modified since an earlier year, that's alright.