Labels in Citations

Some bibliographic reference lists are unnumbered, some are bulleted lists, some have a counting number before each reference, and some have special symbols or author-descriptive labels (such as [Piez 2009]) constructed according to “Harvard rules” or other semantic numbering system. The first decision a publisher or archive needs to make is whether to capture such numbers using <label> or whether all such designators are generated for display or print. A repository archive may choose to preserve all numbers; a publisher may choose to generate them.
Assuming numbers will be preserved, the next decision concerns punctuation and spacing. It is possible to preserve all punctuation and spacing “3.” or “[Lapeyre-Usdin 2009]” or to preserve just the significant portion of the label (the numeral or the name-year) and not preserve the spacing or punctuation: “3” or “Lapeyre-Usdin 2009”. The following samples preserve the label punctuation (and could also preserve label spacing):
...
<ref>
<label>13</label><x>. </x>
<element-citation publication-type="journal"
publication-format="print">
<collab>American College of Dentists, Board of
Regents</collab>
<article-title>The ethics of quackery and fraud
in dentistry: a position paper</article-title>
<source>J Am Coll Dent</source>
<year iso-8601-date="2003">2003</year>
<volume>70</volume>
<issue>3</issue>
<fpage>6</fpage>
<lpage>8</lpage>
</element-citation>
</ref>
...


...
<ref>
<label>13</label><x>. </x>
<mixed-citation publication-type="journal"
publication-format="print">
<collab>American College of Dentists, Board of
Regents</collab>. <article-title>The ethics of
quackery and fraud in dentistry: a position
paper</article-title>. <source>J Am Coll
Dent</source>. <year iso-8601-date="2003">2003</year>;
<volume>70</volume>(<issue>3</issue>):
<fpage>6</fpage>-<lpage>8</lpage>.</mixed-citation>
</ref>
...
Usually the label applies to the reference (<ref>). Citations (<element-citation> or <mixed-citation>) are typically only numbered when multiple citations occur within a single reference. In such cases, the reference is typically numbered in series with the other, single references, and the citations are numbered using a different numbering scheme. For example, a reference numbered <label>4.</label> could have citations inside it labeled “a.”, “b.”, “c.” or “[Gaylord 2005]”, “[Beck 2006]”, “[Usdin 2009]”.