External Link

Link to an external file or resource.


Linking: Use the standard XLink attributes to provide a live link to the external source. The attribute @xlink:href is not required, but should be used to provide the link.
Resource Type: 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 document or document component (such as an article or a chapter) is available in multiple forms, for example, as a means of indicating the online version of a print document. Conversely, a URI that indicates a different book, article, or any other kind of live-linked external reference is usually tagged as <ext-link>. The <uri> element, 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 <ext-link> element is intended to act as a link; a URI <uri> element identifies a URI (such as a URL) in the text, but may or may not be a traversable link; and the <self-uri> points to another form of the same document. To make any of these elements into a live link, add the XLink @xlink:href attribute.
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 | bold | fixed-case | italic | monospace | overline | roman | sans-serif | sc | strike | underline | ruby | named-content | styled-content | sub | sup)*


This element may be contained in:

Example 1

An empty <ext-link> element for which content will be generated:
<sec sec-type="intro">
<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; no text will be generated. The content is @xlink:href attribute, repeated:
<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" orientation="portrait"
     position="anchor" specific-use="online-format" xlink:href="v1"/>
<graphic orientation="portrait" position="float" xlink:href="f1"/>
<graphic id="f1a" orientation="portrait" position="float" xlink:href="dummy1.png"/>
<graphic id="f1b" orientation="portrait" position="float" xlink:href="dummy2.png"/>
<graphic id="f1c" orientation="portrait" position="float" xlink:href="dummy3.png"/>
<graphic id="f1d" orientation="portrait" position="float" xlink:href="dummy4.png"/>


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

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>


Example 5

Identifying and linking to a Clinical Trial (mention in the text):
<p>... Trial registration: <ext-link 
 ext-link-type="clinical trials" 
 (<ext-link ext-link-type="uri"