I am a Captain for a 121 carrier and have a question on an A.T.C. communication procedure from A.I.M. 5-3-3-a-1-(a); reporting leaving altitude, both climbing and descending. Many pilots now, both civilian and military backgrounds, are reading back A.T.C. clearances to climb or descend verbatim. Example: (A.T.C.): "United 8, climb and maintain FL360" - (Pilot): "United 8, climb and maintain FL360". I learned many years ago that to satisfy the A.I.M. referenced above, a proper acknowledgment would be, "United 8 is departing FL340 for FL360". It seems that in a non-radar environment, a call leaving altitude is required, but though this is true in a radar environment also, it is overlooked. Our company Flight Operations Manual specifically states to report leaving altitude. I emailed the F.A.A. in Washington 2 weeks ago with this question but have yet to receive an answer. Technically, am I correct in demanding that my First Officers report leaving altitude? Thank you for your replies!