In late 2021, the Library of Congress adopted several exemptions to the Digital Millennium Copyright Act (DMCA) provision prohibiting circumvention of technological measures that control access to copyrighted works. In other words, they created a set of exceptions to the general legal rule against cracking digital locks on things like DVDs, software, and video games. The exemptions are set out in regulations published by the Copyright Office. They went into effect on October 28, 2021 and last until October 28th, 2024. This guide is intended to help preservationists determine whether their activities are protected by the new exemptions. It includes important updates to the first edition to reflect changes in the rule to allow offsite access to non-game software, along with a few other technical changes.