definition[el.definition]

The definition for a dictionary entry, scientific units, etc.

The definition should be a short nounal phrase definining the subject of the entry. Definitions should not include commentary, implementations, equations or formulae (unless the subject is one of these) or examples. The description element can be used for these.

The definition can be in any markup language, but normally XHTML will be used, perhaps with links to other XML namespaces such as CML for chemistry.

example

From the IUPAC Dictionary of Medicinal Chemistry

<entry id="a7" term="Allosteric enzyme">
  <definition>An <a href="#e3">enzyme</a>
that contains a region to which small, regulatory molecules
("effectors") may bind in addition to and separate from the
substrate binding site and thereby affect the catalytic
activity.
  </definition>
  <description>On binding the effector, the catalytic activity of the
<strong>enzyme</strong> towards the substrate may be enhanced, in
which case the effector is an activator, or reduced, in which case
it is a de-activator or inhibitor.
  </description>
</entry>

Content Model

( ANY [lax])*

source[att.source]

An attribute linking to the source of the information

A simple way of adding metadata to a piece of information. Likely to be fragile since the URI may disappear.

example

<list>
  <definition source="foo.html#a3">An animal with four legs</definition>  
  <definition source="http://www.foo.com/index.html">
    An animal with six legs</definition>
</list>