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<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>”.
In citations, a <label> can be used to preserve the prefix number for the reference or citation, for example, “25.” or “[Richardson 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 figure label below might best be pronounced as “figure 3”, avoiding the issues of the abbreviation, any non-breaking-space character, and the roman numerals. 
<label alt="figure 3">Fig&#x00A0;III.</label>
Attributes
alt

Multi-lang Attributes

lang-focus
lang-focus-custom
lang-group
lang-source
lang-source-custom
lang-translate
lang-variant
lang-variant-custom

Base Attributes

id
xml:base
xml:lang
Models and Context
May be contained in
<abstract>, <ack>, <address>, <aff>, <answer>, <answer-set>, <app>, <app-group>, <array>, <author-notes>, <back>, <bio>, <boxed-text>, <chem-struct>, <chem-struct-wrap>, <corresp>, <def-item>, <def-list>, <disp-formula>, <disp-formula-group>, <disp-quote>, <element-citation>, <explanation>, <fig>, <fig-group>, <fn>, <fn-group>, <glossary>, <graphic>, <kwd-group>, <legend>, <list>, <list-item>, <media>, <mixed-citation>, <note>, <notes>, <option>, <product>, <question>, <question-preamble>, <question-wrap-group>, <ref>, <ref-list>, <related-article>, <related-object>, <sec>, <statement>, <supplementary-material>, <table-wrap>, <table-wrap-foot>, <table-wrap-group>, <textual-form>, <trans-abstract>, <verse-group>
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 | 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
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>
...
Figure 
...
<sec>
 <title>Outcome data</title>
 ...
 <p>Figure <xref ref-type="fig" rid="F2">2</xref> shows that
  overall there was no significant difference between day hospital
  and alternative forms ...</p>
 <fig id="F2">
  <label>Figure 2</label>
  <caption><p>Odds of death or poor outcome in patients
   receiving day hospital care or alternative services (random
   effects model). Heterogeneity between trials is presented
   as χ<sup>2</sup></p></caption>
  <graphic xmlns:xlink="http://www.w3.org/1999/xlink"
    xlink:href="fors2662.f2"></graphic>
 </fig>
</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>
...
Note 
...
<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
Mixed citation
...
<ref id="B1">
 <label>1</label>
 <mixed-citation publication-type="book">
  <collab>Research Unit of the Royal College of 
  Physicians and British Geriatric Society</collab>. 
  <source>Geriatric day hospitals: their role 
  and guidelines for good practice</source>. 
  <publisher-loc>London</publisher-loc>:
  <publisher-name>RCP</publisher-name>; 
  <year iso-8601-date="1994">1994</year>.
 </mixed-citation>
</ref>
...
Element citation
...
<ref id="B8">
 <label>8</label>
 <element-citation publication-type="journal">
  <person-group person-group-type="author">
   <name><surname>Weissert</surname>
    <given-names>W</given-names></name>
   <name><surname>Wan</surname>
    <given-names>T</given-names></name>
   <name><surname>Livieratos</surname>
    <given-names>B</given-names></name>
   <name><surname>Katz</surname>
    <given-names>S</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="pmid">6772889</pub-id>
 </element-citation>
</ref>
...
Hypothesis in <statement> 
<article dtd-version="1.4">
 <front>...</front>
 <body>
  ...
  <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>
  ...
 </body>
 <back>...</back>
</article>
Alternative Spanish and English Variants of a Figure 
...
<fig id="f0001" lang-group="f0001"
  position="float" fig-type="scatter-graph" 
  xml:lang="en" lang-variant="translation" 
  lang-source="translator" lang-focus="secondary">
 <label>Figure 1.</label>
 <caption><p>Evolution of the repetition rate in all sequences</p></caption>
 <graphic xlink:href="RIYA_A_1889289_F0001_OC-en.jpg" 
    content-type="color" specific-use="web-only"/>
</fig>

<fig id="f0005" lang-group="f0001"  
  position="float" fig-type="scatter-graph" 
  xml:lang="es" lang-variant="original" 
  lang-source="author" lang-focus="primary">
 <label>Figura 1.</label>
 <caption><p>Evolución de la tasa de repetición en  
  todas las secuencias</p></caption>
  <graphic xlink:href="RIYA_A_1889289_F0005_OC-es.jpg" 
    content-type="color" specific-use="web-only"/> 
</fig>
...
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