Date orders
>You mean like the way ISO 8601 defines the international standard date format - i.e. 2011-02-13?
YMD is a logical order. In this format, you can order alphabetically and things still sort chronologically. It also is logical in the sense that the units are in (reverse) order of unit size.
UK format - DMY is also logical (it is simply the inverse of the above). Again, (reverse) alphabetical sorting still yields the correct chronological order. It is also in order of ascending unit size (As we do with normal numbers) so is probably the most consistent system.
US style - MDY makes no logical sense at all. You are not even using unit sizes in order. It would be like saying 123 as "Three and One hundred and Twenty".