This pack contains several placeholder tracks for unreleased dungeons, and replacements for overworld and plots music.
They are all .ogg files less than a single kb in size. If you wish to insert music of your own in these, replace the files with an .ogg of the exact same file name.
To use them in-game, toggle the appropriate options in your Player Enchanted Book (PEB).
With the music delay enabled, there will be 10 minutes between the start of each of these tracks. With it disabled, there will be 4 minutes between the start of each track.