Used to mark text that should appear lower than the baseline and slightly smaller; inferior or subscript text.


arrange Arrangement of Subscripts and Superscripts
id Document Internal Identifier
specific-use Specific Use
xml:base Base

Content Model

<!ELEMENT  sub          (#PCDATA %emphasized-text;)*                 >

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 | private-char | chem-struct | inline-formula | tex-math | mml:math | abbrev | milestone-end | milestone-start | named-content | styled-content | fn | target | xref | sub | sup | x | break)*


Any combination of:

This element may be contained in:

<abbrev>, <abbrev-journal-title>, <addr-line>, <aff>, <alt-title>, <anonymous>, <article-title>, <attrib>, <award-id>, <bold>, <chapter-title>, <chem-struct>, <code>, <collab>, <comment>, <compound-kwd-part>, <compound-subject-part>, <conf-acronym>, <conf-loc>, <conf-name>, <conf-num>, <conf-sponsor>, <conf-theme>, <copyright-holder>, <copyright-statement>, <corresp>, <def-head>, <degrees>, <disp-formula>, <edition>, <element-citation>, <email>, <etal>, <ext-link>, <fax>, <fixed-case>, <funding-source>, <funding-statement>, <given-names>, <gov>, <history>, <inline-formula>, <inline-supplementary-material>, <institution>, <issue>, <issue-part>, <issue-sponsor>, <issue-title>, <italic>, <journal-subtitle>, <journal-title>, <kwd>, <label>, <license-p>, <meta-name>, <meta-value>, <mixed-citation>, <monospace>, <named-content>, <on-behalf-of>, <overline>, <p>, <part-title>, <patent>, <phone>, <prefix>, <preformat>, <product>, <publisher-loc>, <publisher-name>, <rb>, <related-article>, <related-object>, <role>, <roman>, <sans-serif>, <sc>, <self-uri>, <series>, <series-text>, <series-title>, <sig>, <sig-block>, <source>, <speaker>, <std>, <std-organization>, <strike>, <string-conf>, <string-date>, <string-name>, <styled-content>, <sub>, <subject>, <subtitle>, <suffix>, <sup>, <supplement>, <surname>, <target>, <td>, <term>, <term-head>, <textual-form>, <th>, <title>, <trans-source>, <trans-subtitle>, <trans-title>, <underline>, <unstructured-kwd-group>, <uri>, <verse-line>, <volume>, <volume-id>, <volume-series>, <x>, <xref>

Example 1

Ordinary subscripts:

<fig id="f7" orientation="portrait" position="float">
<label>FIG. 7.</label>
<p>(2Si=O-H)<sup>+</sup> complex formation mechanism via three-fold 
coordination of the O atom with subsequent H 1<italic>s</italic> level 
lowering and extra electron donation to a DB in SiO<sub>2</sub> and to 
the Si conduction band in the SiO<sub>2</sub>/Si interface, respectively.
Electron excitation over to the SiO<sub>2</sub> conduction band denoted 
by a symbol × is not allowed because the energy needed for excitation over 
to SiO<sub>2</sub> conduction band is larger than the H 1<italic>s</italic> 
level lowering.</p>
<graphic orientation="portrait" position="float" xlink:href="f7"/>

<p>This article by Peter Wilmshurst (10 October 1998, pp 996-9)
used the incorrect abbreviation for inspired partial pressure
of oxygen. The abbreviation should have been Pi<sc>o</sc><sub>2</sub>
not Fi<sc>o</sc><sub>2</sub>.</p>

Example 2

As shown formatted above, a subscript and superscript in a “stacked” arrangement:

<p>The <italic>Escherichia coli argU</italic> gene encodes a minor arginine
tRNA, tRNA<sup arrange="stack">Arg</sup><sub arrange="stack">UCU</sub>,
which corresponds to the rare codon AGA and possibly AGG ...</p>