The <arg-value> argument specifies an
attribute value for the enclosing action. If the
type attribute is structured, then the content of
<arg-value> must be a set of <arg-component>'s.
If the type attribute is other than structured,
then each of the enclosed tokens are evaluated and
the resulting string values are concatenated to
form a value.
Examples
<arg-value>
<token-attr name="Surname"/>
<token-text>, </token-text>
<token-attr name="Given Name"/>
</arg-value>
<arg-value type="structured">
<arg-component name="string">
<token-text>EN</token-text>
</arg-component>
<arg-component name="string">
<token-text>JP</token-text>
</arg-component>
</arg-value>