units Units

The units of measure in which the size or length of a cited work is expressed. (For example, a @units value might record “pages”, “minutes”, “seconds”, or “linear-feet”.)

Usage/Remarks

Display units in the text versus @units values

The full canonical name of the unit should always be expressed as the value of the @units attribute. But sometimes a publisher wants the displayed unit value to be different, for example “p.” as the display for “pages” or “lvs” as the display value for “leaves”. How to record unit display values is different for mixed and element citations.
Mixed Citations — Best Practice for mixed-style citations (<mixed-citation>) is to place the unit display text into the free text of the citation. The unit display should never be inside the <size> element.
...
<mixed-citation publication-type="conf-proc">
 ...
 <size units="pages">385</size> p. <comment>(Progress in
 brain research; vol. 147)</comment>
</mixed-citation>
...
Element Citations — In element-style citations (<element-citation>), there is no one Best Practice for recording displayable units. The units in the text can be handled in several ways:
  • Best if possible. If the @units attribute value has been tagged consistently, the unit display text can be generated on display and does not have to be included in the element content:
    <size units="pages">256</size>
    
  • If the publisher or archive does not wish to generate text based on the attribute (or cannot, for example, if the attributes have not been tagged consistently), there are no good answers, but the display of the unit text can be handled (awkwardly):
    • Included as content of a <comment> or an <x> element
      <element-citation>
      ...
      <size units="pages">256</size><comment> p.</comment>
      ...
      </element-citation>
      
    • If all else fails. Included as content in the <size> tag:
    <size units="pages">256 pages</size>
    
REQUIRED on element: <size>
Value Meaning
Text, numbers, or special characters Names the units of measure in which the size is expressed, for example, “MB”.
Restriction @units is required; it must be provided if the element is used.
Tagged Sample

@units for a cited proceedings’ page count

...
<mixed-citation publication-type="conf-proc">
 ...
 <size units="pages">385</size> p. <comment>(Progress in
 brain research; vol. 147)</comment>
</mixed-citation>
...
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