Datetime structure excerpted from ISO8601:1988

There are several elements that allow a date and time argument to be applied. HTML 4.0 requires a specific format be followed in the presentation of this information. It does not state why.

The format is specifically stated as follows:

YYYY

= a year designation of four (4) numeric digits based on the Gregorian Calendar. All four digits are required.

-

= the field separator

MM

= a month designation of two (2) numeric digits with a leading zero being significant. "00" through "12" is the acceptable range.

-

= the field separator

DD

= the day of the month in numeric format with a leading zero being significant. "00" through "31" is the acceptable range.

T

= a separator indicating the start of the time field

hh

= a two numeric digit hour descriptor based on the 24 hour clock (i.e. 2:00 p.m. would be 14:00 hours). "00" through "24" is the acceptable range.

:

= the field separator for the time record

mm

= a two numeric digit minute descriptor with a leading zero being significant. "00" through "59" is the acceptable range.

:

= the field separator for the time record

ss

= a two numeric digit second descriptor with a leading zero as significant. The seconds field cannot be omitted in this structure. "00 through "59" is the acceptable range.

TZD

= the Time Zone Descriptor. This is usually expressed in terms of offset from Coordinated Universal Time (the old Grenwich Mean Time) and is expressed in plus or minus hours and minutes and must follow the same precepts as noted above.