Ok, I admit, all things JLR SDD, CAN and related electronics has become an obsession.
But, learning about such things can be a daunting task.
Fortunately, there are folks out there who are willing to share.
If you are curious about CAN on a practical basis, you might check out:

https://bxproject.co.uk/blog/categor...ronics/canbus/

The author, _M, is very knowlegible and a natural tutor.

If you are working on or interested in a CAN project, let's hear for you on the forum and advance understanding of JLR CAN together.

Bill