<label> Label (of an Equation, Figure, Reference, etc.)

Number and/or prefix word placed at the beginning of display elements (for example, equation, statement, figure).

Usage/Remarks

As an example, a label placed at the beginning of an equation (<disp-formula>) could be a number such as <label>Equation 3.</label>, <label>(3)</label>, or <label>3.</label>. A label before a statement, such as a Proof or Lemma, could be a word such as <label>Proof</label> or <label>Hypothesis</label>.
Many objects can take explicit labels. For example, a <label> can contain the number or symbol used as a prefix character for a footnote that is placed at the point of the footnote reference. Similarly, the number and any prefix word associated with the title or the caption of a <fig> can be marked as a <label>, for example, “<label>Figure 3.</label>”, “<label>Exhibit 2.</label>”, or “<label>3.</label>”.
A <label> can be used to preserve the prefix number for a reference or citation “25.” or “[Lapeyre 2010]”. This can be useful when reconstructing untagged cross-references.
Accessibility
Sometimes a <label> needs to be pronounced in a way that is not reflected in its content or its tagging. The @alt attribute can be used to record the pronunciation for screen readers and other accessibility devices. For example, the element figure that follows might be pronounced as “Figure 3”.
<label alt="figure 3">Fig&#x00A0;III.</label>
Attributes

Base Attributes

Models and Context
May be contained in
Description
Any combination of:
Content Model
<!ELEMENT  label        (#PCDATA %label-elements;)*                  >
Expanded Content Model

(#PCDATA | email | ext-link | uri | inline-supplementary-material | related-article | related-object | hr | bold | fixed-case | italic | monospace | overline | overline-start | overline-end | roman | sans-serif | sc | serif | strike | underline | underline-start | underline-end | ruby | alternatives | inline-graphic | inline-media | private-char | chem-struct | inline-formula | tex-math | mml:math | abbrev | index-term | index-term-range-end | milestone-end | milestone-start | named-content | styled-content | fn | target | xref | sub | sup | x | break)*

Tagged Samples
In table
...
<table-wrap id="t2" orientation="portrait" position="float">
 <label>Table II.</label>
 <caption>
  <p>Models to approximate the bound frequencies as waves 
   in X→M (<inline-graphic id="g1" xlink:href="d1"/>: Rotational, 
   <inline-graphic id="g2" xlink:href="d2"/>: Vibrate in <italic>y</italic> 
   direction, <inline-graphic id="g3" xlink:href="d3"/>: Vibrate in
   <italic>x</italic> direction, <inline-graphic id="g4" xlink:href="d4"/>: 
   Vibrate mainly in <italic>y</italic> direction including a small 
   portion of vibration in <italic>x</italic> direction, 
   <inline-graphic id="g5" xlink:href="d5"/>: Vibrate mainly in 
   <italic>x</italic> direction including a small portion of vibration 
   in <italic>y</italic> direction).</p>
 </caption>
 <table border="1">...</table>
</table-wrap>
...
In figure
...
<sec id="bid.36">
 <title>Microbial Genomes</title>
 <p>... A CON entry, containing instructions on how to put
  the pieces back together, is also made. The CON entry
  contains descriptor information, such as source organism
  and references, as well as a join statement providing
  explicit instructions on how to generate the complete
  genome from the pieces. The Accession number assigned 
  to the CON record is also added as a secondary Accession
  number on each of the pieces that make up the complete
  genome (see <xref ref-type="fig" rid="bid.37">Figure 2</xref>).
  <fig id="bid.37">
   <label>2</label>
   <caption>
    <title>A GenBank CON entry for a complete bacterial 
     genome.</title>
    <p>The information toward the <italic>bottom</italic> of the 
     record describes how to generate the complete genome
     from the pieces.</p>
   </caption>
   <graphic xmlns:xlink="http://www.w3.org/1999/xlink"
     xlink:href="ch1f2" mimetype="image/jpeg"/>
  </fig>
 </p>
 ...
</sec>
...
... 
<fig id="f3" position="float">
 <label>FIG. 3.</label>
 <caption>...</caption>
 <alternatives>
  <graphic specific-use="print" xlink:href="1.4821168.figures.highres.f3.zip"/>
  <graphic specific-use="online" xlink:href="1.4821168.figures.online.f3.jpg"/>
 </alternatives>
</fig>
...
In table with supplementary material
...
<table-wrap id="pbio-0020328-t002" position="float">
 <label>Table 2</label>
 <caption>
  <title>Genes Activated in the Mother-Cell Line of Gene Expression</title>
 </caption>
 <alternatives>
  <graphic xlink:href="pbio.0020328.t002.tif"/>
  <table frame="box" rules="all" cellpadding="5">...</table>
  <supplementary-material id="S1" xmlns:xlink="http://www.w3.org/1999/xlink"
    xlink:title="local_file" xlink:href="pbio-0020328-t002.xls"
    mimetype="application/vnd.ms-excel">
   <label>Supporting Material</label>
   <caption>
    <p>Supplementary Microsoft Excel file (raw study data) supplied by authors.</p>
   </caption>
  </supplementary-material>
 </alternatives>
 <table-wrap-foot>...</table-wrap-foot>
</table-wrap>
...
In reference
...
<ref id="c35">
 <label>35.</label>
 <note>
  <p>The geometric optimization and electronic transport properties are 
   all calculated by a developed <italic>ab-initio</italic> software package 
   Atomistix ToolKit, which is based on the spin-polarized density-functional 
   theory combined with the non-equilibrium Greens functions. ...</p>
 </note>
</ref>
...
In citations
Element citation
...
<ref-list>
 ...
 <ref id="B8">
  <label>8</label>
  <element-citation>
   <person-group person-group-type="author">
    <name><surname>Weissert</surname>
     <given-names>W</given-names></name>
    <name><surname>Livieratos</surname>
     <given-names>B</given-names></name>
   </person-group>
   <article-title>Effects and costs of day-care
    services for the chronically ill: a randomized
    experiment</article-title>
   <source>Medical Care</source>
   <year iso-8601-date="1980">1980</year>
   <volume>18</volume>
   <fpage>567</fpage>
   <lpage>584</lpage>
   <pub-id pub-id-type="publisher-id">WES-6772889</pub-id>
  </element-citation>
 </ref>
 ...
</ref-list>
...
Mixed citation
...
<ref-list>
 ...
 <ref id="B8">
  <label>8</label>
  <mixed-citation>
   <string-name><surname>Weissert</surname>,
   <given-names>W</given-names></string-name>,
   <string-name><surname>Livieratos</surname>,
   <given-names>B</given-names></string-name>.
   <article-title>Effects and costs of day-care 
   services for the chronically ill: a randomized 
   experiment</article-title>. <source>Medical Care</source>
   <year iso-8601-date="1980">1980</year>; <volume>18</volume>:
   <fpage>567</fpage>&ndash;<lpage>584</lpage>.
   <pub-id pub-id-type="publisher-id">WES-6772889</pub-id>.
  </mixed-citation>
 </ref>
 ...
</ref-list>
...
Hypothesis in <statement>
...
<sec>
 ...
 <p>Industrial buyers categorise foreign countries
  according to their level of technological achievement
  and subsequently differentiate their perceptions of
  these countries accordingly. ... The following
  hypothesis is posited:
  <statement>
   <label>Hypothesis 1</label>
   <p>Buyer preferences for companies are influenced 
    by factors extrinsic to the firm attributable to, 
    and determined by, country-of-origin effects.</p>
  </statement>
 </p>
</sec>
...