The data in packages usually uses a special format without a clear extension, but in. I can see this one in the index
{5b64713a-e5ab-4deb-b515-cc8a4ee471c2} RockKit uvf.drum.y.user 2024-05-06T01:39:29 2024-05-06T01:39:29 S362
Can you consider modifying the uvf.drum.y.user? I'm not sure if I'm right
You can consider anything.
But, you must accept responsibility if something goes wrong and the pack becomes unusable! Since this modification is outside the ordinary scenario,
the risk is yours...
I know this isn't the answer you're looking for, but I'm not Yamaha and Yamaha do not publicly document their software internals.
Good luck -- pj