Events -- online -- how to markup?

Hi,

When marking up events what is considered best practice for events that can
be attended online?

Events appears to be requiring a physical location via Place.

Example


   1.   <div itemprop="location" itemscope itemtype="http://schema.org/Place">
   2.     <a itemprop="url" href="wells-fargo-center.html">
   3.     Wells Fargo Center
   4.     </a>
   5.     <div itemprop="address" itemscope
itemtype="http://schema.org/PostalAddress">
   6.       <span itemprop="addressLocality">Philadelphia</span>,
   7.       <span itemprop="addressRegion">PA</span>
   8.     </div>
   9.   </div>


Would omitting address and just including url be appropriate?

Using google's data highlighter address is listed as required -- how
closely does the data highlighter match the spec?


Thanks for the advice,


Ali