One of the publication history dates that may be preserved for a book or book component, such as when it was last updated. This element acts (as does the related element <pub-date>) as a wrapper element for date elements, such as <day>, <month>, and <year>, which are usually given numeric values, as well as for <string-date> and <season>, which are just text strings.


Conversion Note: It is best practice to tag individual date elements (such as <year>) whenever possible. Use <string-date> for the narrative form of a date when necessary, for example, when a date has no month or year specified. However, even inside a <string-date> the named date components, such as <year>, can even be specified.

The NCBI Book DTD and NCBI Collection DTDs allow <string-date> both inside <date> and at the same level as <date>. This is the most flexible for allowing the archive to preserve any publisher’s structure.


date-type Type of Date

Related Elements

The tag set includes several date elements. For the date of publication of a book (metadata) use the element Publication Date <pub-date>. For the copyright date of a book (metadata) use the copyright year element <copyright-year>. The <date> element is be used for dates concerning a book or book component (e.g., a chapter) publication history such as the date last updated (also metadata). For the publication date of a cited work in a bibliographic reference <citation>, use the individual elements <month>, <day>, and <year>. If no month or month/day construction is given within a <citation>, and the only date is a season or a textual form of the date, such as “Third Quarter”, use the <season> element inside the <citation> element.

Model Information

Content Model

<!ELEMENT  date         %date-model;                                 >


The following, in order:

This element may be contained in:

<history> History: Document History

Tagged Example

<title>GenBank: The Nucleotide Sequence Database</title>
<date date-type="created">
<date date-type="updated">
<alternate-form xmlns:xlink="http://www.w3.org/1999/xlink" 
alternate-form-type="pdf" xlink:href="ch1d1"/>
<p>The GenBank sequence database is an annotated collection of all publicly 
available nucleotide sequences and their protein translations. This database 
is produced ...</p>