at the destination, then the time the end of the packet is received could be used instead of the time the beginning is received.

Instantaneous packet delay variation is the difference between successive packets--here RFC 3393 does specify the selection criteria--and this is usually what is loosely termed jitter, although jitter is also sometimes the term used for the variance of the packet delay. As an example, say packets are transmitted every 20 ms. If the second packet is received 30 ms after the first