Well when I talk about a remix I mean something that definitely involves either newly composed music or newly written lyrics. That is the only kind of remix I know. If you don’t change the music or lyrics significantly I’d consider it a mix or edit.
But you’re right: I thought I had read it somewhere in the documentation, but instead it was on the forum:
PS: I did find something in the documentation:
Distinctiveness
A work’s distinctiveness is based on the artists who contributed to its final output, and whether a work is derived from another original work. Examples of works that are distinct:
[…] a mashup of multiple original works
If a mashup of let’s say 50% one existing work and 50% from another constitutes a new work how can a remix consisting of 50% material from an existing work and 50% new creation not be new work based on the old one?