Reference to an object within the document (for example, a table, a bibliographic citation).
This element may be used to reference anything that has an attribute of type @id. This single element takes the place of the many named types of references (such as figure references, table references, and footnote references) that are common in many tag sets.
Best Practice: The @ref-type attribute (of the <xref> element) can be used to preserve information concerning what type of element is being pointed to by the cross-reference.
Accessibility: Sometimes a <xref> 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 cross-reference to a figure that follows might be pronounced as “Figure 4”.
See <xref alt="figure 4">Fig&#x00A0;IV.</xref>
Display/Formatting Note: The content of the reference (if present) will be displayed as the link.
<!ELEMENT xref (#PCDATA %xref-elements;)* >
(#PCDATA | email | ext-link | uri | inline-supplementary-material | related-article | related-object | hr | bold | italic | monospace | overline | overline-start | overline-end | roman | sans-serif | sc | strike | underline | underline-start | underline-end | alternatives | inline-graphic | 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)*
Any combination of:
<abbrev>, <addr-line>, <aff>, <alt-title>, <anonymous>, <article-title>, <attrib>, <award-id>, <bold>, <book-title>, <chapter-title>, <chem-struct>, <collab>, <comment>, <compound-kwd-part>, <conf-acronym>, <conf-loc>, <conf-name>, <conf-num>, <conf-sponsor>, <conf-theme>, <contrib>, <contrib-group>, <copyright-statement>, <corresp>, <def-head>, <degrees>, <disp-formula>, <edition>, <element-citation>, <email>, <etal>, <ext-link>, <fax>, <funding-source>, <funding-statement>, <given-names>, <gov>, <inline-formula>, <inline-supplementary-material>, <institution>, <issue>, <issue-part>, <issue-title>, <italic>, <kwd>, <label>, <license-p>, <meta-name>, <meta-value>, <mixed-citation>, <monospace>, <named-content>, <nav-pointer>, <on-behalf-of>, <overline>, <p>, <part-title>, <patent>, <phone>, <prefix>, <preformat>, <product>, <publisher-loc>, <publisher-name>, <related-article>, <related-object>, <role>, <roman>, <sans-serif>, <sc>, <see>, <see-also>, <see-also-entry>, <see-entry>, <self-uri>, <series>, <sig>, <sig-block>, <source>, <speaker>, <std-organization>, <strike>, <string-conf>, <string-date>, <string-name>, <styled-content>, <sub>, <subject>, <subtitle>, <suffix>, <sup>, <supplement>, <surname>, <target>, <td>, <term>, <term-head>, <th>, <title>, <trans-source>, <trans-subtitle>, <trans-title>, <underline>, <unstructured-kwd-group>, <uri>, <verse-line>, <volume>, <volume-id>, <volume-series>, <xref>
...
<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" mime-subtype="gif"/>
</fig>
</p>
...
</sec>
...
...
<p>Allocation of tags to individual molecules is outlined in
<xref ref-type="fig" rid="F2" alt="figure two">Fig.&#x00A012;2</xref>.
First, the complete repertoire of tags in a plasmid library is ligated
to the entire population of cDNAs ...
After separating loaded microbeads from unloaded microbeads
by FACS, as shown in <xref ref-type="fig" rid="F4"
alt="figure four">Fig.&#x00A012;4</xref>,
the hybridized DNA is ligated to the anti-tag, covalently
attaching one strand of the DNA to the microbead's surface.
This permits easy removal of the noncovalently attached
strand.</p>
...
JATS-link1.ent