<unitdate> Date of a Unit

<unitdate> is a child element of <did> used to encode the creation year, month, or day of the described materials. It may in the form of text or numbers and either a simple date or range. Use @normal to indicate an ISO 8601-standardized form of the date. Other types of dates should be encoded within <date>, <daterange>, <datesingle>, or <dateset>. It is comparable to ISAD(G) element 3.1.3, and MARC fields 245 subfield f for inclusive dates, 245 subfield g for bulk dates, or 260 subfield c.

Consider using the new <unitdatestructured> instead, to express the relevant dates in a machine-processable form. Use <unitdate> if you also wish to record dates intended solely for human audiences.


  • @altrender – not required. Use if the content of the element should be displayed or printed differently than the rendering established in a style sheet for other occurrences of the element.
  • @audience – not required. Use to set whether the element’s contents will be visible to external users or to internal ones. Possible values are: “internal” and “external.”
  • @calendar – not required. Default value is “gregorian.”
  • @certainty – not required. May be used to indicate degree of precision used in dating—”circa,” “approximately,” “after,” etc.
  • @datechar – not required. May be used to characterize the nature of the dates, such as “creation” or “modification.”
  • @encodinganalog – not required. May contain information to map this tag to a particular element in another schema.
  • @era – not required. May be used to indicate the era in which the date falls. Default values is “ce” for common or “Christian” era.
  • @id – not required. Creates an ID for element. Can be used for linking.
  • @label – not required. This can be used when a meaningful display label for an element can’t be derived by the stylesheet from its name. It is available in all <did> subelements.
  • @lang – not required. Three-letter code that indicates the language in which the element’s contents were written. It should come from ISO 639-2b.
  • @normal – not required. An ISO 8601 (or otherwise specified) numeric form of the date used for machine reading and comparison, i.e. YYYY-MM-DD, YYYYMMDD, YYYY/YYYY, etc. Should particularly be used if the text within the element is not written out as YYYMMDD.
  • @script – not required. Four-letter code that indicates the script in which the element’s contents were written. It should come from ISO 15924.
  • @unitdatetype – not required. Use to record whether the unit dates are bulk or inclusive. Possible values: bulk, inclusive.

Child Elements

<unitdate> may contain text, as well as <abbr>, <emph>, <expan>, <foreign>, <lb />, <ptr/>, and <ref>.


Use DACS Section 2.4, Date. Required. (or <unitdatestructured> is) (DACS 2013, pp.24-27)


  <unittitle>Quilting Technologies Department Records</unittitle>
  <unitdate normal="1978/2020" unitdatetype="inclusive">1978-2020</unitdate>
  <physdesc>10 linear feet</physdesc>
  <physdesc>221 GB</physdesc>
<unitdate normal="1997">1997</unitdate>

Changes from EAD 2002

<unitdate> gained @lang and @script. @type was changed to @unitdatetype. Its use was restricted to <did>. It may no longer contain <archref>, <bibref>, and <title>, as well as deprecated <extptr>, <extref>, <linkgrp>

EAD3 Tag Library Entry

View the official tag library entry for <unitdate>