C: Date

Definition: A date associated with an event in the life cycle of the resource.

Obligation: Recommended.

What is this element?

The Date element is used to capture information about any dates associated with a resource. This can include time, if that is important information for people trying to find that resource. The Date element provides for searches to be restricted to resources relating to a certain date - when the resource was created, modified, valid or issued.

If you describe a group of items in aggregate, as a collection, give the date range of the creation dates of the resources that make up the collection.

If the resource being described is only valid for a certain time, or if it is only valid up to one date from another date, then use the valid refinement.

For an agency, give the dates of key events in its history, such as establishment, disestablishment (including corporatisation) etc.

For a service, give the date the service was first provided from - enter using the 'created' refinement.

Metadata creators need to decide when a change is just a modification to a resource (use the modified refinement), and when changes to a resource are so significant that they actually create a new resource - which will require its own set of metadata.

This situation is mostly likely to arise with respect to web pages that may be regularly updated. For example, adding an additional Subject term might reflect a minor extension of the item (a modification) or simply be better description. Replacing the Subject terms with others because the content has been rewritten, or "refocused" would be a major change and a new metadata record would be appropriate. Other elements that would flag major changes are Audience, Creator, Description, Function, Title, and Mandate. [Refer also Section B.6] If the date is not known, do not guess it.

Date and other elements

Where the content of a resource refers to a period or time, describe this using the Coverage element. The Date element describes the resource itself, not the content of the resource.

If a service is open to requests only seasonally (possibly a period) enter those dates as Availability. (This puts all the information about how to obtain the resource in one place.) Use Date for the period of the "season", instead of Availability or Coverage. Consider using the 'valid' refinement of Date.

Qualifiers

Refinements

When Date is used, you should include a 'refinement', to help users understand what the date refers to:

• available - date (often a range) that the resource will become or did become available.
• created - the date the resource (not the metadata record) was created. For agencies this is the date from which they come into effect, in their mandate.
• modified - the date on which the resource was modified. Date may be repeated with this refinement, but remember to consider if the extent of modification is such that a new record should be created. For example, this may be used for internal organisational restructures, but for the movement of functions from or to agencies, and for changes in status, e.g. from department to SOE, create a new metadata record.
• valid - the date when the resource becomes valid, or ceases to be valid, or the date range for when the resource is valid. For agencies this is the date from which they cease to exist, as specified in the legal instrument which disestablishes them.
• issued - the date on which the resource was made formally available in its current form (e.g. publication date).

Encoding schemes

If the metadata creation tool you use does not handle the encoding for you, you need to follow the appropriate encoding schemes to ensure the information is correctly read by other applications.

Dates

Encode in the formats specified by the W3C-DTF "Date and Time Formats" profile of ISO 8601 : 2000 "Data elements and interchange formats - information interchange - representation of dates and times" [2000], supplemented by DCMI Period which adds methods of describing open-ended periods which ISO 8601 : 2000 lacks.

• Specify as much of the date and time as is useful - typically year, month and day; but, for example, year might be all that is appropriate.
• Use small dashes '-' to separate the date components.
• Use the forward slash "/" as a separator for the two dates defining a period, for example, 2001-01-01/2001-01-31

For example:

• ISO 8601 : 2000 - a date:
  YYYY-MM-DD (e.g. 1997-07-16)
• ISO 8601 : 2000 - Periods of Time when start and end dates are known:
  YYYY-MM-DD/YYYY-MM-DD (eg1997-07-16/1997-8-17)
• DCMI Period - when the start or end date are not known:
  start=YYYY-MM-DD
  end=YYYY-MM-DD

Examples