One of the processing dates that may be preserved for a historical book, for example 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.


This element has the same model and attributes in this DTD as it does in the NCBI Book DTD; new attribute values (for example, “translated” and “transcribed”) have been added for the date-type attribute.

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 Historical DTD allows <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. Tighter DTDs created from the base Suite may choose to use one or the other in preference.


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 <pub-date>. For the copyright date of a book (metadata) use the copyright year element <copyright-year>. The <date> element is be used for historical dates concerning a book or book component (e.g., a chapter) such as the date transcribed. For the publication date of a cited work in a bibliographic reference (<citation> or <nlm-citation>), use the individual elements <month>, <day>, and <year>. If no month or month/day construction is given within a <citation> (or <nlm-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> (or <nlm-citation>) element. A purely textual date or partial date can be recorded as a <string-date>.

Model Information

Content Model

<!ELEMENT  date         %date-model;                                 >


The following, in order:

Tagged Example

<book-id pub-id-type="other">waln-1</book-id>
<book-title>An account of
the asylum for the insane, established by the
Society of Friends, near Frankford, in the
vicinity of Philadelphia . . . from the
Philadelphia journal of the medical and
physical sciences, for August, 1825.
<publisher-name>Benjamin &amp; Thomas Kite</publisher-name>
<printer-loc>Locust Street, Philadelphia</printer-loc>
<date date-type="first-published">