easy to read/parse integer format. Used mainly for dates < Jan-1-1970 (e.g.
birth-dates) and quick-and-easy month/day comparisons without using tm structs
and time_t conversions (and all their peculiarities). Obviously these integers
do not contain any *time* information.
Created time_t to/from decimal-coded date functions (obviously only useful for
dates in the 1970-2038 range).