Zander believed that it is not possible to dual-license something under both CC-BY-SA and public domain because all licenses are based on having copyright, whereas public domain means the lack of copyright. Zander preferred copyleft licenses for BIPs. Tom Zander suggested that BIPs should be licensed as public domain with a CC-BY option. It was pointed out that while BIP 1 requires public domain or OPL, it does not forbid other licenses. Similarly, BIP 2 allows for other acceptable licenses but does not recommend them. Despite the goal of no longer allowing public domain as the only copyright option, BIP 2 does not forbid releasing work under public domain in jurisdictions where it is recognized as legal. Many BIP authors have previously chosen public domain as the only option.On October 15, 2016, Tom Zander and Marco Falke discussed the licensing of BIPs. Zander had dual-licensed BIP 134 under OPL and CC-BY-SA for future acceptance of CC-BY-SA without needing permission from all authors to remove the OPL. Falke pointed out that BIP 2 does not allow public domain as the only copyright option, to which Zander responded that public domain was never the only option.In an email exchange between Tom Zander and Luke Dashjr, they discussed licensing options for BIPs. Zander suggested public domain (CC0) or a CC-BY option, while Dashjr added MIT/BSD licenses. Dashjr explained that BIP 1 only allows OPL and public domain, so BIP 2 can be available under OPL until it activates. Dashjr clarified that CC0 and public domain are different. Dashjr was asked to reach out to the community to ensure BIP 2 has been heard and discussed. France and Germany do not recognize public domain, while GPL is valid anywhere copyright laws exist.On October 15, 2016, a discussion took place on the Bitcoin development mailing list regarding the licensing of BIPs. Marco Falke suggested licensing BIPs under CC0 with a CC-BY option, while Tom Zander disagreed and suggested a requirement for "Share alike" and an optional "Attribution." It was argued that more restrictive licenses are not suitable for BIPs and that the BIP repository is not the place to promote open access. BIP 2 allows for such licenses but does not recommend them. Clarity around proposed changes and reasoning was encouraged. The discussion concluded with the suggestion to move forward with BIP 2 if there were no objections.In a conversation on the Bitcoin Development mailing list about licensing for BIPs, it was suggested that "Share alike" be required and "Attribution" be optional. However, it was pointed out that there is no Creative Commons license option that requires Share Alike and allows Attribution as an option. CC0, MIT/BSD, or CC-BY were proposed as suitable licenses for BIPs. The suitability of more restrictive licenses and promoting open access in the BIP repository were also discussed. BIP 2 allows for such licenses but does not recommend them. The email thread concluded with the suggestion to move forward with BIP 2 if there were no objections.Luke Dashjr announced that the Open Publication License (OPL) will no longer be acceptable for BIPs. He recommended replacing OPL with one or two Creative Commons licenses, with the choice between CCO and BY-SA licenses alongside public domain. The Open Publication License, created in 1999, was superseded by Creative Commons licenses. Luke-jr made updates to BIP 2, replacing BIP 1, and introduced changes such as the acceptance of non-image auxiliary files, required email addresses for authors, and disallowing Markdown format. The updated BIP 2 was open for review with the aim of completion by Christmas.