Exit numbers: Distance based number or sequential?

[mapman1071]

I believe the MUTCD advises fixing the zero point for mileposting and distance-based exit numbering at the start of route or entry point in a state (as applies), but I am not sure this guideline has been elevated to a Standard.  Depending in part on whether it has or not, oddities like I-17 in Arizona with its zero point at (approximately) MP 184 are likely to persist.

I-17 First Mile is 194

[Scott5114]

Originally the exit numbers on 3dis in Oklahoma (in Tulsa, anyway, no idea if OKC did the same thing) would start with the same numbering that the parent highway had at their junction! That means that I-244 inherited I-44's exit numbering, starting at 92, and dinky little I-444 had exits 94A—D and 96A—C! (One 94D sign hung around on I-444 long after this system was abandoned and the other exit numbers removed.)