1990 to 1999: Expansion of the World Wide Web and the Rise of Dot-Coms - The Technical and Social History of Software Engineering - page 258

Table 8.2 Possible Date Format Key That Uses One Additional Digit
The examples shown in Table 8.2 illustrate what might be done using only a
single extra digit. For many date and timekeeping purposes, it might be desirable
to include not only century, year, month, and day information but also weeks,
hours, minutes, seconds, and even milliseconds. Thus, if a date key is used to
identify which format is being utilized, even the following 16-digit date format
could be used if needed:
x-yyyy-MM-ww-dd-hh-mm-ss
In this 16-digit format, x is the date code; yyyy represents the year; MM rep-
resents the month; ww represents the week of the year; dd represents the day; hh
represents the hour; mm represents the minute; and ss represents the second. Even
16 digits are not enough precision for some uses, so the schema could be extended
down to the nanosecond level. If it takes 20 digits or more, any known date format
might be incorporated into the schema, but then conservation of space is irrelev-
ant.
For a universal date format, there may be hundreds or even thousands of date
variants that would need specific keys. Therefore, a four-digit key followed by 20
digits of date information should be able to accommodate any known calendar and
to operate over arbitrarily long time periods.
The ISO standard date format is not adequate for scientific purposes. For deal-
ing with geological and astronomical time periods, spans of millions of years must
be accommodated, and most of this time would be in the BC era and hence re-
quire negative numbers. For astronomical time, billions of years must be accom-
modated. Indeed, for astronomical purposes, the calendars of other planets such as
Mars may eventually need to be accommodated.