Math Equations

The JATS and NLM Book DTDs allow math to be encoded in a number of ways: as MathML, as a pointer to an image file, or as a combination of the two. How your export has been set up depends on the uses that are going to be made of your XML and the needs of any downstream partners such as compositors and online hosts.

For example, this MathType equation:

when exported as MathML, gives this XML:

<disp-formula id="e2">
<mml:math id="m1">
<mml:mrow>
<mml:msqrt>
<mml:mrow>
<mml:msup>
<mml:mi>a</mml:mi>
<mml:mn>2</mml:mn>
</mml:msup>
<mml:mo>+</mml:mo><mml:msup>
<mml:mi>b</mml:mi>
<mml:mn>2</mml:mn>
</mml:msup>
</mml:mrow>
</mml:msqrt>
</mml:mrow>
</mml:math>
<label>(2)</label>
</disp-formula>

Note that the values of the <mml:math> id attribute are allocated sequentially on export and do not necessarily correspond to any equation number used in the text [if, in this example, equation (1) had been typed from the keyboard, so that equation (2) was the first MathType object in the document]. Values of the <disp-formula> id attribute are based on the equation numbers. Values of the <disp-formula> id attribute for unnumbered equations are treated similarly to unnumbered figures and tables: the first equation is "e", the second is "e___1", etc.

If the export is instead set to add graphic pointers to equations, the following XML is output:

<graphic position="anchor" xlink:href="9388_007-m1" xmlns:xlink="http://www.w3.org/1999/xlink"/>

where 9388_007 is the document ID, set in the Document Information dialog. Note that, by default, the file extension is not included in the XML (see the previous discussion). The default naming convention for equation images is based on the document ID and "mn", where n is the sequential number of the equation object (note that this is not related to any equation numbers that may or may not be associated with the equation in the text).