Thanks, that's what I assumed (because it makes sense). For metric you often go two orders of magnitude smaller, but I'm thinking a good amount of the reason to usually go straight to millimeters instead of also using decimeters is that decimeters just can't easily represent many common fractions of a meter (1/4, 3/4, 1/3, 2/3), and a base 10 system can never represent some of those perfectly without resorting to a mixed format.