We sometimes use the height of a doorknob above the floor as a frame of reference for a height of 1 m. I just put that presumption to the test here in my apartment in Midland, Texas, USA, and I measure 950 mm from the floor to the tangent at the top of the doorknob collar. If you have a chance, please try measuring your doorknob height and see how it compares.
Thanks, Paul
