Coff #278,
I seem to recall both of those datum points being used to determine the longitudinal datum when positioning the aircraft in "rigging position" during servicing. The Lateral position used, I recall, was across the canopy rails. My fondest memory of the use of the canopy rails was a combined OUAS/LUAS and 6AEF beer call when all of our Chipmunks held a Firkin of Hook Norton Bitter across the rear cockpit rails. Possibly the last time that I enjoyed a pint within 2 feet of an Aircraft. Honest
Smudge
