What is a servlet's "display-name" for?

The <display-name> element appears to be a valid sub-element of the <servlet> element as per the Servlet 2.5 deployment descriptor XSD. That is, according to Eclipse's XML validator, this:

<servlet>
    <servlet-name>FooServlet</servlet-name>
    <display-name>FooServlet</display-name>
    <servlet-class>com.bar.servlet.FooServlet</servlet-class>
</servlet>

is a valid servlet-mapping, while this:

<servlet>
    <servlet-name>FooServlet</servlet-name>
    <random-tag-name>OMGWTFBBQ</random-tag-name>
    <servlet-class>com.bar.servlet.FooServlet</servlet-class>
</servlet>

is not (which seems reasonable enough).

What's the display-name actually used for? I haven't been able to dig up anything informative on it.