An easy to use, compact code for dates is invaluable to sort files chronologically, and saves precious room on crowded Excel listings and DVD titles.
Extending conventional hex code, a single character represents months ranging from Jan  through August , September , October [A], November [B], and December [C]. Similarly, the days of the month range from  through 31 [V].
To create files, checks, DVDs, etc. for this century, the codes range from Jan 1 2000  through December 31 2099 [99CV].
I routinely add a date suffix to file names, e.g. revisions of the same file might be called: [study063U], [study063V], [study0641]. So the file names will sort chronologically in systems lacking accompanying creation dates.
This code is very easy to create using three mnemonics: hex F , and the PK disease , . I also know 30 and 31 are [U] and [V].
It turns out that converting back to conventional dates is needed much less frequently than creating codes since the compact chronological sort meets most of my needs.
If you need to refer to historical or future dates, how about this?
So with the addition of only one character for the century, you can represent a range of 32 centuries past and future, from the year 1 through the year 3199. Of course, you can still make the first character "understood", just as the "20" is understood in today's date when written 3/28/06.
BCE dates and dates from 3200 CE forward are left as an exercise for the gentle reader.