The International Standards Organisation' standard, number 8601 is an international standard for date and time representations.
For a plain-language overview of ISO 8601, we recommend the ISO 8601 summary by Markus Kuhn
RFC 3339 defines a profile of ISO 8601 for the use in Internet protocols and standards. It explicitly excludes durations and dates before the common era. The more complex formats like week numbers and ordinal day are not permitted (see RFC 3339, section 5.6).
- Should we restrict microformats' use of ISO 8601 to RFC 3339 values? Andy Mabbett
- How should dates before the common era be marked up? Andy Mabbett
- ISO 8601 on Wikipedia
- ISO 8601:2004(E) from ISO (zip-pdf, 228KB)
- Summary of 8601 by ISO
- Technical Committee ISO/TC 154, Processes, data elements and documents in commerce, industry and administration.
- The Mathematics of the ISO 8601 Calendar
- Current date in week date and ordinal date format
- ISO 8601 at the Open Directory Project
- W3C Specification about UTC Date and Time and IETF Internet standard RFC 3339, based on ISO 8601