Do not confuse dates in this element with dates and time indicated in the element COVERAGE.TEMPORAL. The various qualified elements for DATE are for administrative events such as final creation of the resource or its issuance or last modification. DATE has to do with the physical instantiation of a resource, not the intellectual content found within a resource.

A properly formatted date consists of an ASCII date string of 10 characters for the standard date format YYYY-MM-DD (1998-01-24), unless time stamps are included (T08:15:30-05:00).

• Year (YYYY) is defined as 0000 to 9999.
• Month (MM) is defined as 01 to 12.
• Day (DD) is defined as 01 to 28, 29, 30 or 31 as applicable.
• The separator between date fields isa hyphen, (-).

If needed, the time stamp (Thh:mm:ssTZD) directly follows the date designation. It begins with the letter "T" to flag that a time stamp is present.

The time format (hh:mm:ss) consists of two digit designations for hours, minutes and seconds (19:20:30) in a 24 hour clock mode. If necessary, the seconds may be further defined by a decimal fraction of a second (19:20:30.45).

The time zone designator (TZD)completes the statement and consists of a + or - sign and the number of hours a particular time zone deviates from Greenwich Mean Time.

If a date is approximate, add a question mark but separate the date from the question mark by a space so that the question mark is not interpreted as part of the date value by a search engine. Generally, year or year-month-day will provide enough precision.

If the full date is unknown, month and year (YYYY-MM) or just year (YYYY) may be used. Many other schema are possible, but if used, they may not be easily interpreted by users or software.