BS ISO 8601:2004

Foreword
Introduction
1 Scope
2 Terms and definitions
  2.1 Basic concepts
  2.2 Time units, nominal durations and time intervals
  2.3 Representations and formats
3 Fundamental principles
  3.1 Basic rules
  3.2 Time scales
  3.3 Representations and format representations
  3.4 Characters used in the representations
  3.5 Expansion
  3.6 Leading zeros
  3.7 Mutual agreement
4 Date and time representations
  4.1 Date
  4.2 Time of day
  4.3 Date and time of day
  4.4 Time interval
  4.5 Recurring time interval
5 Date and time format representations
Annex A (informative) Relationship to ISO 2014, ISO 2015,
                      ISO 2711, ISO 3307 and ISO 4031
Annex B (informative) Examples of representations
Bibliography

Applies whenever representation of dates in the Gregorian calendar, times in the 24-hour timekeeping system, time intervals and recurring time intervals or of the formats of these representations are included in information interchange.