New() in constructor
<p>Can someone tell me what New() in the following method constructor means?  I know that TEvent inherits from CompositePresentationEvent but what does new() mean?</p>

<pre><code>protected void RaiseEvent&lt;TEvent, TParameter&gt;(TParameter parameter) where TEvent : 
    CompositePresentationEvent&lt;TParameter&gt;, new()
    {
        EventAggregator.GetEvent&lt;TEvent&gt;().Publish(parameter);
    }
</code></pre>
