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Alternative Versions
Processing Alternatives
The <alternatives> element holds
multiple, logically equivalent (substitutable) versions of the same information object.
The typical case is a graphic (<graphic>)
which is provided in multiple formats (such as a TIF, a JPEG, and an SVG image) or
in multiple resolutions. These
various formats offer processing alternatives for use by production personnel or by
software in presenting the work to the user. For example, a high-resolution TIF image
may be included and designated for use in printing while the same image, provided
as a
lower-resolution JPEG file, may be designated for use in web display.
Other potential use cases include:
- An equation (<disp-formula> or <inline-formula>) that is available as an image as well as both TeX- and MathML-tagged versions;
- A video for online display and a thumbnail that represents one image from the video for use in print versions of the work (<media>); or
- A table (<table-wrap>) for which both NISO JATS XHTML-inspired Table tagging and an image have been provided.
The <alternatives> element can be used
everywhere that <graphic> and <media> are allowed. For example, <alternatives> can be used inside a <fig> as part of the large group of options that can be
inside a Figure. (See Figures/Graphics/Media.) This example shows a single figure (“Figure
3”) with four processing alternatives—3 graphics in different image
formats and one media file:
...
<fig id="Fig12a">
<label>Figure 3</label>
<caption>
<title>Large Poodles</title>
</caption>
<alternatives>
<graphic xlink:href="poodle12.tif"/>
<graphic xlink:href="poodle12.jpeg"/>
<graphic xlink:href="poodle12.gif"/>
<media mimetype="image/png" xlink:href="poodle-jump12.png"/>
</alternatives>
</fig>
...
Similarly, a table (<table-wrap>) may
be provided in multiple formats; for example, the table below has three alternative
formats: an XML-tagged table, the equivalent image file, and a textual version with
the
tabular look created by lines and spacing.
...
<table-wrap>
<object-id>...a DOI...</object-id>
<label>Table 6.</label>
<alternatives>
<table frame="box" rules="all" cellpadding="5">...an XHTML-inspired formatted table...</table>
<preformat>...a tabular form with spaces and tabs...</preformat>
<graphic xlink:href="tab437.jpg">...a JPEG of the same table...</graphic>
</alternatives>
</table-wrap>
...
Alternatives Including Mixed-content Elements
The element <alternatives> may contain graphical alternatives, XML-tagged alternatives, and one or more
alternatives that contain text characters. For example, the alternatives within an
equation might be a JPEG image of the equation, an XML equation tagged in MathML,
and a plain text equivalent equation such as a + b = c. The <textual-form> element can be used inside <alternatives> to hold such plain text version alternatives.
Not for Differing Audience/Use Alternatives
Where to use <alternatives>
— The <alternatives> element contains processing alternatives for a single display object such as a graphic or a table. Typical uses include:
- A graphic in three resolutions
- A video and a still image.
Where NOT to use <alternatives>
— The element <alternatives>
should not be used to tag multiple versions of content that are intended for different audiences or document-building
uses.
Do not use <alternatives> for:
- Not: Two versions of a section, a short one for print (e.g., to save paper) and a significantly longer one for online display;
- Not: Alternative versions of a <boxed-text> for different print products (one for the magazine and one for the journal); or
- Not: Multiple versions of semantically related content intended for different audiences (for patients versus for doctors).
These intentional/semantic alternatives are different from the case of multiple formats
of the same graphic, in part because there is a structural difference; for example,
a given section does or does not contain this boxed-text. There is also a difference
in complexity between this case and that of the multiple graphic formats, in that
software can pick one alternative graphic based on external factors, whereas, for
the semantically distinct objects, the software must build a different structural
tree.
JATS provides the @specific-use attribute to record semantic or intentional distinctions, for example, that certain
paragraphs are only for print:
<p specific-use="print-only">See the latest updates on our website: http://www.mulberrytech.com</p>
This leaves the burden of how to treat these similar-content objects for display to
the local processor.
The @specific-use attribute can be placed on all the block-level structures, that is, on paragraphs,
figures, sections, and all the block display objects. There is no recommended set
of values, but publishers have used “print-only”, “web-only”, “online-only”, “voice-only”, “specific-product-name”, etc.