RFC: Improve License Clarity Scoring

[DennisClark]

Replace the current license clarity scoring, which was originally associated with the Clearly Defined project, with the following structure:

Proposed Element Definitions

License Clarity

License Clarity is a set of criteria that indicate how clearly, comprehensively and accurately a software project has defined and communicated the licensing that applies to the project software. Note that this is not an indication of the license clarity of any software dependencies.

Score

The license clarity score is a value from 0-100 calculated by combining the weighted values determined for each of the scoring elements: Declared license, Identification precision, License texts, Declared copyright, Ambiguous compound licensing, and Conflicting license categories.

Declared license

When true, indicates that the software package licensing is documented at top-level or well-known locations in the software project, typically in a package manifest, NOTICE, LICENSE, COPYING or README file. Scoring Weight = 40.

Identification precision

Identification precision indicates how well the license statement(s) of the software identify known licenses that can be designated by precise keys (identifiers) as provided in a publicly available license list, such as the ScanCode LicenseDB, the SPDX license list, the OSI license list, or a URL pointing to a specific license text in a project or organization website, Scoring Weight = 40.

License texts

License texts are provided to support the declared license expression in files such as a package manifest, NOTICE, LICENSE, COPYING or README. Scoring Weight = 10.

Declared copyright

When true, indicates that the software package copyright is documented at top-level or well-known locations in the software project, typically in a package manifest, NOTICE, LICENSE, COPYING or README file. Scoring Weight = 10.

Ambiguous compound licensing

When true, indicates that the software has a license declaration that makes it difficult to construct a reliable license expression, such as in the case of multiple licenses where the conjunctive versus disjunctive relationship is not well defined. Scoring Weight = -10 (note negative weight).

Conflicting license categories

When true, indicates the declared license expression of the software is in the permissive category, but that other potentially conflicting categories, such as copyleft and proprietary, have been detected in lower level code. Scoring Weight = -20 (note negative weight).

[pombredanne]

@LeChasseur FYI, we would be interested in your take on this!

[pombredanne]

@DennisClark the only edits I made were to add tags for titles and bold

[LeChasseur]

The idea sounds good to me. If possible I wouldn't give the same weight to NOTICE, LICENSE, COPYING or README if more of one of these categories contains license informations. To my experience most projects use LICENSE or COPYING. The README contains sometimes additional information that isn't a declaration of the applicable license. I would give such information less weight if LICENSE or COPYING exists.
However, GNU projects seems to have a slightly different system to use COPYING-files (e.g. https://github.com/gcc-mirror/gcc). This needs consideration.
The term "NOTICE" comes from Apache-2.0. Mostly there are additional licenses and copyright notices if the main license is Apache-2.0.
In any case, it is very helpful for peopole doing license compliance work to have a suggestion which is the main license of the project.

[JonoYang]

@DennisClark

I've began making modifications to the license clarity scoring, which I have created as a separate plugin for now. You can test out the new license clarity scoring by using the --license-clarity-score-2 and --classify option.

scancode -clip --classify --license-clarity-score-2 <package directory> --json-pp <json output location>

I had some questions about how the following criteria should be handled.

Ambiguous compound licensing

When true, indicates that the software has a license declaration that makes it difficult to construct a reliable license expression, such as in the case of multiple licenses where the conjunctive versus disjunctive relationship is not well defined. Scoring Weight = -10 (note negative weight).

• Does this mean that in the case where we scan a package and get different license expressions from the key files, but there are no expressions that contain AND or OR, that we should modify the score by -10? I am assuming that if no license conjunction or disjunction is in the license expression, that no choice of license was detected from key files.
• Do you know of any packages that would be a good test case for this?

Conflicting license categories

When true, indicates the declared license expression of the software is in the permissive category, but that other potentially conflicting categories, such as copyleft and proprietary, have been detected in lower level code. Scoring Weight = -20 (note negative weight).

• I noticed in the previous license clarity scoring plugin that we checked for license consistency, where we check that the file-level licenses are consistent with the licenses detected in top-level key files. Should we do the same here or is it enough to check that the file-level licenses do not conflict with the top-level licenses, even if the file-level licenses are not stated at the top-level?
• This is a more general licensing question, but is there a conflict where we detect copyleft-limited licensed files in a permissively licensed package? For example, a permissively licensed package that contains files licensed under gpl-2.0-plus WITH autoconf-simple-exception-2.0