I don’t think any of this is that precise. Not in that way. Certainly not between makers and model shops, as opposed to within working groups, where people end up using similar terms and methods, even without having policies or meetings about it.
Even just looking at a specific foot, rather than an anthropometric generalization of one, how do you draw a dot for the big MTP joint “precisely”? It’s a complex, organic shape, obscured by complex, organic tissues. Even standardized methods and apparatuses for locating and measuring, like the Brannock ball slider, remain substantially subjective in use. The Brannock patent text admits it. And a lot of shops and fitters basically just use the Brannock for stick length.
Neither does the foot really bend along a crisp line. If we built, say, sandal soles out of two pieces, with gate hinges to join, we wouldn’t have the “break-in” period of convincing the sole to flex, but it would never be comfortable, no matter how well you placed the hinge. Most people’s joints don’t fall along a straight line, but along a curve. Those curves can change as the foot rotates within a shoe. The pads of the feet are rounded, and could readily callous if repeatedly pinched, like my hands have calloused over barbells and pull-up bars.
The amazing thing is despite all this fuzziness, there are fitters who can take 1D or 2D measurements and produce shoes that function beautifully on first try. There’s also a big subjective part to fit, and I’ve yet to meet anybody who claims it to get it right first try every time. But it’s amazing to think how good they have to be to get lucky so often.
The way a particular maker measures feet may affect where he puts a point or a line. How they carve or shape around those marks can also differ. There are both error bars and deliberate choices at basically every step. The trick seems to be to find combinations that function overall, as systems. Every individual step that one maker uses could cause misfits if subbed into another maker’s system.
That’s a big part of why I find this so interesting! And, frankly, why I’m so grateful for the videos on lastmakers from folks like Kirby Allison, even if trite, snoody paean montages about “craftsmanship” and “tradition” make me queasy.