Often the pulse sequencing to be supplied to servos is refered to as PPM
No, PPM is the multiplexed stream between TX and Rx in an R/C system, so in a single frame, an individual channel's pulses are identified by their position relative to the sync pulse, which is simply a longer 'low' than the 'low' between channel pulses.
The individual channel pulses are indeed PWM, because their width defines the servo setting.
If you want info on R/C systems, go to an R/C website.