Similar to caps lock being ctrl when held and escape when tapped, I set up return to be ctrl when held and return when tapped. Nice keyboard symmetry this way too.
Progressive lenses need much more accuracy to be fitted correctly. This means a mono-PD (separate PD for each eye, not just the distance PD halved) and also a height, usually from "datum" measured for each eye too. This measurement would be different depending on the frame and how it sits/adjusted to your face.
This means the frame must be chosen and fitted to you before any of these are measured.
It becomes a 2D measurement.
There is a lot more to it (vertex distance, pantoscopic tilt etc) but the above is the absolute minimum.
I still occasionally listen to it.