I don't have the maintenance manual in front of me. But the Owner's manual, starting pg 329 has a lot of information.
The Service's are classified A thru H, signifying the approximate number of hours required to perform the service. A = 1 hour, H = 8.
So, Service C would be a 3 hour service.
In the owners, manual it tells you the key sequence to see what a particular Service calls out (i.e. the definition of what is in Service C).
It also states that if you have inadvertantly reset a required Service WITHOUT performing it, you must have MB reset your system.