Why no SPDX license identifiers in documentation files?

[schlotter]

The Zephyr Project is a great example of making use of SPDX. Every source code file clearly states its license via the SPDX license identifier:

# SPDX-License-Identifier: Apache-2.0

(Example from zephyr/cmake/cfb.cmake)

In contrast, for documentation files this is not the case: Zephyr's ReStructured Text files do not contain a SPDX licence identifier (Example).

Only the rendered documentation contains a footer:

© Copyright 2015-2023 Zephyr Project members and individual contributors. Last updated on Jul 14, 2023.

Why is this the case?

[nashif]

@kestewart is it common to have SPDX in doc files?

[schlotter]

I finally managed to talk to @kestewart on OSS EU 😀

Yes, we should have SPDX license identifiers in every file. Documentation files are under a license, too, so a SPDX license identifier should be in their header. The SPDX license identifier does not need to show up in the rendered documentation.

According to Zephyr's Project Charter, 14.c), Zephyr documentation is made available via Creative Commons Attribution 4.0 International License.

[henrikbrixandersen]

CC: @kartben