External Link

Link to an external file or resource.


Use the standard XLink attributes to provide a live link to the external source.
The @ext-link-type attribute can be used to give an indication of the type of resource to which the external link points. While this Tag Set does not constrain the values of this attribute, and ordinary text is acceptable, the suggested values include:
Enzyme nomenclature. See http://www.chem.qmw.ac.uk/iubmb/enzyme/
GenBank identifier
Translated protein-encoding sequence database
HighWire Press intrajournal
Protein data bank. See http://www.rcsb.org/pdb/
Plant gene register. See http://www.ebi.ac.uk/~textman/pgr-htdocs/pgr/
Protein Information Resource. See http://pir.georgetown.edu
Protein Information Resource. See http://pir.georgetown.edu
PubMed Central identifier
PubMed identifier
Swiss-Prot. See http://www.ebi.ac.uk/swissprot/
Astronomical Object Identifier
Digital Object Identifier
File transfer protocol
Website or web service

Related Elements

<self-uri> is used when a book or book component is available in multiple forms, for example, as a means of indicating the online version of a print book or book part. Conversely, a URI that indicates a journal article, a companion book, or any other kind of external reference is usually tagged with <ext-link>. <uri>, although allowed everywhere <ext-link> is used, is more typically part of an address, information concerning a contributor, or part of a reference citation. Loosely put,
  • an external link element (<ext-link>) is intended to act as a link;
  • a URI element (<uri>) identifies a URI (such as a URL) in the text, but may or may not be a traversable link; and
  • a <self-uri> points to another form of the same book or book part (such as the PDF version of an online HTML eBook).
The address element <email> is allowed as part of a paragraph as well as inside an address. There are two ways to treat an email address in text: as an <email> element or as an <ext-link> element. If both a textual phrase (“the Moody Institute’s email address”) and a mailto URL are required, the <ext-link> element should be used.
The elements used in an address may include the address class elements: <addr-line>, <city>, <country>, <fax>, <institution>, <institution-wrap>, <state>, <phone>, and <postal-code> and the address linking class elements: <email>, <ext-link>, and <uri>.


Content Model

<!ELEMENT  ext-link     (#PCDATA %ext-link-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 | 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)*


This element may be contained in:

<abbrev>, <address>, <addr-line>, <aff>, <alt-title>, <anonymous>, <array>, <article-title>, <attrib>, <award-id>, <bold>, <book-title>, <book-volume-id>, <book-volume-number>, <chapter-title>, <chem-struct>, <chem-struct-wrap>, <code>, <collab>, <comment>, <compound-kwd-part>, <conf-acronym>, <conf-loc>, <conf-name>, <conf-num>, <conf-sponsor>, <conf-theme>, <contrib>, <contrib-group>, <copyright-statement>, <corresp>, <data-title>, <def-head>, <degrees>, <disp-formula>, <disp-formula-group>, <edition>, <element-citation>, <email>, <etal>, <ext-link>, <fax>, <fig>, <fig-group>, <fixed-case>, <funding-source>, <funding-statement>, <given-names>, <gov>, <graphic>, <index-entry>, <inline-formula>, <inline-supplementary-material>, <institution>, <issue>, <issue-part>, <issue-title>, <italic>, <kwd>, <label>, <license-p>, <media>, <meta-name>, <meta-value>, <mixed-citation>, <monospace>, <name-address-wrap>, <named-content>, <nav-pointer>, <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>, <see>, <see-also>, <see-also-entry>, <see-entry>, <self-uri>, <series>, <serif>, <sig>, <sig-block>, <source>, <speaker>, <std-organization>, <strike>, <string-conf>, <string-date>, <string-name>, <styled-content>, <sub>, <subject>, <subtitle>, <suffix>, <sup>, <supplement>, <supplementary-material>, <surname>, <table-wrap>, <table-wrap-group>, <target>, <td>, <term>, <term-head>, <th>, <title>, <toc-div>, <toc-entry>, <trans-source>, <trans-subtitle>, <trans-title>, <underline>, <unstructured-kwd-group>, <uri>, <verse-line>, <version>, <volume>, <volume-id>, <volume-series>, <volume-title>, <xref>

Example 1

An empty <ext-link> element for which content will probably be generated for display:
<p>... The highest 16S rDNA sequence similarity  
value of 98&#x0025; was obtained for the 
<italic>D. maris</italic> 16S rDNA sequence (GenBank 
accession no. <ext-link ext-link-type="gen"
xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="Y18883"/>)
and for the <italic>D. maris</italic> DSM 43672<sup>T</sup>
16S rDNA sequence (GenBank accession no. <ext-link
ext-link-type="gen" xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:href="X79290"/>) ...</p>

Example 2

An <ext-link> element with content:
<fig id="f1" orientation="portrait" position="float">
<label>FIG. 1.</label>
<p>(a) Schematic of the working principles of HFM, (b) a typical application
scheme for an electric bias in HFM, (c) regulation the conformations and
dynamics (trapping, concentration, and sudden stretching) of λ-DNA molecules
in HFM, and (d) schematic of the trapping location regulation (enhanced online).
[URL: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1063/1.4762852.1">
<media id="v1" mime-subtype="avi" mimetype="video" orientation="portrait"
position="anchor" specific-use="original-format" xlink:href="v1"/>
<media mime-subtype="mpeg" mimetype="video" orientation="portrait"
position="anchor" specific-use="archival-format" xlink:href="v1"/>
<media mime-subtype="x-flv" mimetype="video" 
position="anchor" specific-use="online-format"  
<graphic xlink:href="f1"/>
<graphic id="f1a"  xlink:href="dummy1.png"/>
<graphic id="f1b"  xlink:href="dummy2.png"/>
<graphic id="f1c"  xlink:href="dummy3.png"/>
<graphic id="f1d"  xlink:href="dummy4.png"/>
<p>In the mid-1990s, the GenBank database became part of the 
International Nucleotide Sequence Database Collaboration with 
the EMBL database (<ext-link xmlns:xlink="http://www.w3.org/1999/xlink"
ext-link-type="uri" xlink:href="http://www.ebi.ac.uk/">European
Bioinformatics Institute</ext-link>, Hinxton, United Kingdom) and 
the Genome Sequence Database (GSDB; LANL, Los Alamos, NM).
Subsequently, the GSDB was removed from the Collaboration (by
the National Center for Genome Resources, Santa Fe, NM), and
<ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" 
xlink:href="http://www.ddbj.nig.ac.jp/">DDBJ</ext-link> (Mishima, 
Japan) joined the group. ...</p>

Example 3

The <ext-link> element used for email, with content given:
<contrib contrib-type="author">
<name name-style="western">
<aff>Klinik für Strahlentherapie und Radiologische Onkologie,
<institution>Technische Universität München</institution>, 
Munich, Germany (Tel: 49-89-41404517, E-mail:
<ext-link ext-link-type="email" xlink:href="mailto:nuesslin@lrz.tum.de">

Example 4

An <ext-link> identifying the assigning authority for the DOI:
<p>In <italic>Developing Thin Clients Using Amphibious Epistemologies</italic> 
(<ext-link ext-link-type="doi" xlink:href="http://dx.doi.org/10.5555/12345679" 
Josiah Carberry introduced &ldquo;Entrust,&rdquo; a linear-time tool for 
simulating architecture.</p>