The focus of our report is on what we call AI music outputs, meaning any kind of music-related content generated by or with the assistance of AI systems, tools and techniques. The report complements the analysis of laws with a review of practices and contractual arrangements of claiming and attributing authorship and/or ownership by actors in the field of AI music creation. The study covers practices of for-profit AI-powered online music creation services (e.g., AIVA, Endel, Xhail, Boomy, Score/Amper, Jukebox, MuseNet, AI tools of Sony CSL) and of non-profit AI music research projects (e.g., folk-rnn, Melomics).