lyberty.com | eclectic content This page created: 2005-06g-17  |   Content last updated: 2005-06g-28   |   Author: Lyberty   

ISO 8601 (a recommended standard from the International Organization for Standardization)
defines the formatting of the date as follows:



YYYY indicates a 4 digit year,

MM indicates a 2 digit month (with a leading zero for months 1 through 9, i.e. January through September), and

DD indicates a 2 digit date/day (with a leading zero for days 1 through 9).

Note: As of June 2005, the current version
of the Recommended Standard "ISO 8601"
is "ISO 8601:2004".

Sample application:

Use of the ISO 8601 date format for web pages (HTML); metadata format about the page.


<!-- dc.date.created : YYYY-MM-DD -->
<!-- dc.date.modified : YYYY-MM-DD -->
<!-- the most recent 'modified' date indicates 'last-modified on ...' -->

<meta name="created" content="2005-06-17">
<meta name="modified" content="2005-06-17">

// and the DCMI Standard:
// http://www.dublincore.org/documents/usageguide/#html
// http://www.cio-dpi.gc.ca/im-gi/meta/clf-nsi-meta/clf-nsi-meta_e.asp#Date



See also: W3C-DTF / [W3CDTF] - the "Date/Time Format" of the W3C;
a.k.a "W3C Encoding rules for dates and times - a profile based on ISO 8601"
-> human readable format (English)


from http://pandora.nla.gov.au/pan/22964/20050307/www.sims.monash.edu.au/research/rcrg/research/spirt/deliver/techintro.html


RKMS Extension for ISO 8601

ISO 8601 is an international standard for the representation of dates and times. The RKMS Schema extends this standard for two reasons: to reduce the number of possible date and time formats, and to allow open-ended date ranges.

Restricted Date and Time Formats

ISO 8601 describes a wider range of date and time formats than would normally be needed to describe recordkeeping entities. Both software and humans can find this variety of date formats difficult to recognise. For this reason, the RKMS Extension for ISO8601 defines a limited range of date formats likely to meet most recordkeeping requirements.

The RKMS Extension to ISO 8601 adopts the restricted set of date formats specified in the World Wide Web Consortium (W3C) Note on Date and Time Formats (http://www.w3.org/TR/NOTE-datetime). This note aims to simplify use of dates on the World Wide Web. All of the date formats specified in the note are valid ISO 8601 dates.

In summary, the W3C note allows dates to be represented as:

  • Year: CCYY (e.g. 1999)
  • Year and Month: CCYY-MM (e.g. 1999-07)
  • Year and Month and Day: CCYY-MM-DD (e.g. 1999-07-01)
  • Year and Month and Day and Hours and Minutes plus Time Zone offset: CCYY-MM-DDThh:mmTZD (e.g. 1999-07-01T19:30+10:00)
  • Year and Month and Day and Hours and Minutes and Seconds plus Time Zone offset: CCYY-MM-DDThh:mm:ssTZD (e.g. 1999-07-01T19:30:45+10:00)


  • CCYY is a two digit century followed by a two digit year (e.g. '1998' or '0875' )
  • MM is a two-digit month (01 is January, 02 February, and so on)
  • DD is a two digit day of the month (01 through to 31)
  • [T is a flag for systems (not humans) that the day string has ended and a time designation follows]
  • hh is a two digit hour (00 through to 23)
  • mm is a two digit minute (00 through to 59)
  • ss is a two digit second (00 through to 59)
  • TZD is a time zone designator (+hh:mm or -hh:mm)

Open Date Ranges

Some record-keeping metadata requires specification of date ranges. For example, a Business Activity may only have been valid between the years 1949 and 1953. ISO 8601 allows the specification of date ranges using a forward slash (/) to separate dates representing the start and end of the range. For example, "1949/1953". Recordkeeping metadata also requires specification of open date ranges. For example, an Agency may have an operational period from July 1st 1998 until the present date. Open date ranges such as this are not defined in ISO 8601. The RKMS Extension to ISO 8601 allows open date ranges to be specified by extending the ISO 8601 syntax to allow the omission of either the start or end date in the range. Acceptable RKMS date ranges are then:

  • Closed date range: DateTime/DateTime (e.g. 1949/1953-01-01)
  • Date range with unknown start: /DateTime (e.g. /2000-12-31T11:59:59)
  • Date range with no end date: DateTime/ (e.g. 1998-07-01/)



Alternatives defined in the DC Schema:

"Available"; "Issued" ; etc.

For example:

<!-- 'issued' = Date resource was made available, e.g. web page published. -->
<!-- 'modified' = Date resource was updated or changed. -->

HTML Formatted Definitions: http://www.dublincore.org/documents/dces/
XML DTD: http://dublincore.org/2005/06/13/dcq#modified


Further information about date/time formatting, including history and alternate or supplemental approches: ./date_format.html


DTD Sample:

- <rdf:Property rdf:about="http://purl.org/dc/terms/available">
  <rdfs:label xml:lang="en-US">Available</rdfs:label>
  <rdfs:comment xml:lang="en-US">Date (often a range) that the resource will become or did become available.</rdfs:comment>
  <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/terms/" />
  <rdfs:subPropertyOf rdf:resource="http://purl.org/dc/elements/1.1/date" />
  <dc:type rdf:resource="http://dublincore.org/usage/documents/principles/#element-refinement" />
  <dcterms:hasVersion rdf:resource="http://dublincore.org/usage/terms/history/#available-002" />
- <rdf:Property rdf:about="http://purl.org/dc/terms/issued">
  <rdfs:label xml:lang="en-US">Issued</rdfs:label>
  <rdfs:comment xml:lang="en-US">Date of formal issuance (e.g., publication) of the resource.</rdfs:comment>
  <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/terms/" />
  <rdfs:subPropertyOf rdf:resource="http://purl.org/dc/elements/1.1/date" />
  <dc:type rdf:resource="http://dublincore.org/usage/documents/principles/#element-refinement" />
  <dcterms:hasVersion rdf:resource="http://dublincore.org/usage/terms/history/#issued-002" />
- <rdf:Property rdf:about="http://purl.org/dc/terms/modified">
  <rdfs:label xml:lang="en-US">Modified</rdfs:label>
  <rdfs:comment xml:lang="en-US">Date on which the resource was changed.</rdfs:comment>
  <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/terms/" />
  <rdfs:subPropertyOf rdf:resource="http://purl.org/dc/elements/1.1/date" />
  <dc:type rdf:resource="http://dublincore.org/usage/documents/principles/#element-refinement" />
  <dcterms:hasVersion rdf:resource="http://dublincore.org/usage/terms/history/#modified-002" />