Smallest distance

I was properly corrected by David in my earlier use of Lorentz as a
distance measure. Indeed, I was thinking of Planck's distance. I did
not mean to use Planck's constant beyond using it to suggest the idea
of a discrete, quanta of space. I have no ability to say it would be
Planck's. I gather the Planck constant is only applied above the
nuclear level. I would think there would be a measure of size at the
quark level as well.

The measuring device must have units smaller than the item being
measured, right?