It is best practice to tag the publication date, which can be recorded using
ordinary date tags such as
<year>. Several
of the date elements may be used in a citation, including
<day>,
<month>, and
<season>.
Typically, for cited journal articles, the citation will contain only a
<year>:
<year>2008</year>.
All other dates in the citations, if they are tagged, use the
<date-in-citation> element, identifying the type of
date with the
@content-type attribute. For
example, if the resource has a time stamp when it was posted (in addition to the regular
publication date), the time stamp can be recorded as:
<date-in-citation
content-type="time-stamp"/>...</date-in-citation>.
Within bibliographic references (
<element-citation> and
<mixed-citation>),
the most important date to tag for purposes of searching and making the citation into
a live link is the publication date. The most common form of the date is the year
(
<year>), shown in the following
citation which also includes the month:
<mixed-citation publication-type="journal" publication-format="print">
<name>...</name>. <article-title>Links between dietary salt ... and
cardiovascular diseases</article-title>. <source>Physiol Rev</source>.
<year>2005</year> <month>Apr</month>;<volume>85</volume>
(<issue>2</issue>):<fpage>679</fpage>-
<lpage>715</lpage>.
</mixed-citation>
Multiple years may be tagged with separate
<year> elements:
<mixed-citation publication-type="journal">
...
<year>2008</year>–<year>2009</year>; ...</mixed-citation>
or combined into a single year:
<mixed-citation publication-type="journal">
...
<year>2008–2009</year>; ...</mixed-citation>
<element-citation publication-type="book">
... <season>Winter</season><year>2008</year> ...</element-citation>
<mixed-citation publication-type="book">
... <season>Winter</season><year>2008</year> ...</mixed-citation>
Within bibliographic citations (
<element-citation> and
<mixed-citation>),
the
<date-in-citation> element can be used to tag
dates other than the publication date of the cited source, for example, the copyright
date, the date on which the contributor accessed the source, the date the cited
resource was withdrawn, or a time stamp indicating when the work was published, for
continuously or frequently updated works. The
@content-type attribute should be used to identify
the purpose or type of date; for example, if the element contains the date on which
the article was withdrawn, the value of the
@content-type would be
“
withdrawn”.
Here is an example in which
<date-in-citation> was used to record the date on which the cited work was last
updated. If a resource has a time stamp in addition to a publication date, that time
stamp could be recorded using this element with a
@content-type attribute of “
time-stamp”. Such a time stamp is applied to the resource by its creators,
usually as a version indicator, and says nothing about when a contributor examined the
resource, only what version was found at the time of examination. Some online
resources are changing so quickly that a citation to the resource is not complete
without the publication time of the resource. The
@content-type should be used to identify such
time-stamps:
<element-citation>
... <date-in-citation content-type="time-stamp">11:57am</date-in-citation> ...
</element-citation>
<mixed-citation>
... <date-in-citation content-type="time-stamp">11:57am</date-in-citation> ...
</mixed-citation>
Here is an example of the
<date-in-citation> element used to record publication history dates that were noted in
the citation:
<element-citation publication-type="book" publication-format="web">
<collab>CENDI Copyright Working Group</collab>
<source>Frequently asked questions about copyright ...</source>
<comment>[Internet]</comment>
<person-group person-group-type="editor">...</person-group>
...<year>2004</year><month>Aug</month>
<date-in-citation>modified 2006 Sep 2</date-in-citation>
<date-in-citation>cited 2006 Nov 6</date-in-citation>
...</element-citation>
<mixed-citation publication-type="book" publication-format="web">
<collab>CENDI Copyright Working Group</collab>. <source>Frequently
asked questions about copyright: ...</source> [Internet].
<person-group person-group-type="editor">...</person-group>, editors.
...<year>2004</year> <month>Aug</month>
[<date-in-citation>modified 2006 Sep 2</date-in-citation>;
<date-in-citation>cited 2006 Nov 6</date-in-citation>]. ...
</mixed-citation>
Unlike the
<year> element as used in
a publication date where best practice is to tag multiple years with multiple
elements, multiple years in non-publication dates should be tagged in a single
element.
<date-in-citation content-type="copyright">2004
–2009</date-in-citation>
Copyright <date-in-citation content-type="copyright">2004-2009</date-in-citation>
In an
<element-citation>, the same
date could be tagged as follows or the word “Copyright” could be generated for
display.
...
<comment>Copyright</comment>
<date-in-citation content-type="copyright">2004-2009</date-in-citation>
...
When both a copyright year and a publication year are present in the same
citation, the ordinary date tags (
<date>,
<day>,
<month>,
<season> and
<year>) should be
used to record the publication date. Here is a publication date tagged with
<year>:
In contrast, the copyright date is tagged with
<date-in-citation>, naming the type of date as a
copyright date in the attribute:
But when there is a single date in the citation and it is the copyright date, a
publisher or archive must choose whether to tag that single date using the
<year> element or the
<date-in-citation> element. The advantage of tagging
that date as a year is that it gives the citation matching tools (which match on
years) some handle on the date. Therefore, an archive might choose to tag the lone
copyright date as:
<year content-type="copyright">2008</year>
instead of using the
<date-in-citation> element, as would be done when both dates were present.
Some citation dates are prefixed with one or more letters. Some publishers prefix
the year with a copyright symbol or a lower case “c” meaning that this
is a copyright date. In mixed-style citations, these symbols can be preserved directly
in the text, between tagged elements:
<mixed-citation
publication-type="book"> ... ©<year content-type="copyright">2004</year>
...</mixed-citation>
<mixed-citation
publication-type="book"> ... c<year content-type="copyright">2004</year>
...</mixed-citation>
In an element-only style citation, the symbol or the letter should either be
removed entirely and left for the display to infer from the
content-type="copyright" or placed into a
<comment> element.
<mixed-citation
publication-type="book"> ... ©<year content-type="copyright">2004</year>
...</mixed-citation>
<element-citation publication-type="book"> ... <year content-type="copyright">2004</year> ...</element-citation>
In some books or older manuscripts, the lower case “c” could also
stand for “circa”, meaning approximate. Similar information might be
indicated by the prefix or suffix “approx.” or the prefix
“between”. Such terms should be preserved similarly; they should be
left in the text for mixed citations and placed in comments for element
citations.