問73
頻出度★☆☆
OSS (Open Source Software) のライセンスにおけるコピーレフトに関する記述として, 適切なものはどれか。
令和8年度 ITパスポート試験 問73
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This question's explanation and your answers so far.
解説
問 73
Incorrectア
Copyleft does not waive the copyright. On the contrary, it is a mechanism that retains the copyright and uses it as the basis to enforce license conditions (such as the obligation to redistribute under the same license). It is the exact opposite of waiving copyright (public domain), so it is incorrect.
Incorrectイ
Copyleft has no rule that monetary compensation must be demanded for users to use the OSS. In principle, OSS can be used, modified, and redistributed free of charge, and forcing compensation also goes against the definition of open source, so it is incorrect.
Incorrectウ
Under copyleft, when distributing derivative software, disclosure (making available) of the source code including the modified part is required. Saying that the modified part can be distributed while keeping it non-public goes against the purpose of copyleft, so it is incorrect.
- エ
正解 Copyleft is the idea of guaranteeing the freedom to modify and redistribute while retaining the copyright, and passing that freedom on to derivative works as well. Specifically, when distributing a derivative software made by modifying an OSS, it requires that the same license as the original OSS be applied. In this way, the derivative work also keeps the same freedoms (such as disclosing the source code). Therefore, choice エ, which states that the same license as the original OSS must be applied, is appropriate. A representative example is GPL.
ここがポイント
- Copyleft = the idea of retaining the copyright while passing the freedom to modify and redistribute on to derivative works. When distributing a derivative work, applying the same license as the original and disclosing the source code are mandatory (a representative example is GPL).
- Waiving copyright, forcing compensation, and distributing the modified part without disclosure all go against the spirit of copyleft.
用語