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 journal tag sets.
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 | milestone-end | milestone-start | named-content | styled-content | fn | target | xref | sub | sup | x | break)*
Any combination of:
<abbrev>, <abbrev-journal-title>, <addr-line>, <aff>, <alt-title>, <anonymous>, <article-title>, <attrib>, <award-id>, <bold>, <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>, <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>, <related-article>, <related-object>, <role>, <roman>, <sans-serif>, <sc>, <self-uri>, <series>, <series-text>, <series-title>, <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>
<article> <front>...</front> <body> ... <p>... Although there is considerable descriptive literature on day hospital care,<xref ref-type="bibr" rid="B1">1</xref> concern has been expressed that evidence for effectiveness is equivocal and that day hospital care is expensive.<xref ref-type="bibr" rid="B2">2</xref> ...</p> ... </body> <back>... <ref-list> <ref id="B1"><label>1</label> <element-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> </element-citation> </ref> <ref id="B2">...</ref> ... </ref-list> ... </back> </article>
... <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> ...