Name the only license both explicitly called out by the Free Software Foundation as non-free for matters of substance and approved by the Open Source Initiative.
Here’s why the FSF says the RPL is non-free:
1. It puts limits on prices charged for an initial copy. 2. It requires notification of the original developer for publication of a modified version. 3. It requires publication of any modified version that an organization uses, even privately.
For more on why these might be problems see debian-legal tests for Debian Free Software Guidelines compliance.
Further trivia: The Artisitc License is the only OSI-approved license rejected by the FSF for matters of wording:
We cannot say that this is a free software license because it is too vague; some passages are too clever for their own good, and their meaning is not clear.