A reference playlist is one that is useful mainly as a reference rather than as something you would actually play from beginning to end. It may contain several whole albums that fit a certain criterion, being useful mainly as a way to find more music of a particular sort. I have made three so far, and each uses a different kind of criterion. One collects together music by a set of related artists, one collects together covers of music by a set of related groups, and one collects together music within a particular sub-genre. If you have your own reference playlist, or you can suggest albums I should add to mine, please post here. These are my three reference playlists. Note that embedded playlists show no more than 200 tracks, but these all have more than that. So, you will need to use Spotify to view the whole lists.
Yesmen collects together music that members of Yes have done outside of Yes:
Progressive Rock Covers collects together covers, usually already together in various tribute albums, of major progressive rock groups, such as Yes, Genesis, Rush, King Crimson, Supertramp, and Pink Floyd.
Classitronic collects together performances of classical music on synthesizers and other electronic instruments.
Since links to the playlists were trying to embed them instead, I took them out. You can find them in Spotify by clicking on my signature.