<othermeta>The <othermeta> element can be used to identify properties not otherwise
included in <metadata> and to assign name/content values to those
properties. The @name attribute identifies the property and the
@content attribute specifies the property's value. All
<othermeta> elements are considered part of the topic's metadata and
should be reflected in the output as appropriate for the output medium.
Category: Prolog (metadata) elements