Online events

I am trying to mark up a site with schema.org markup and have come across
something that I believe is an omission.

We have a number of events some are conferences or meetups, but a lot are
webinars, the latter case causes two potential problems.

1: is that the location field is blank
2: is that there isn't a clear way to mark the URI for the webinar.

It would seem to me that a URI could be used for the location. Perhaps with
a specific event class VirtualEvent  to indicate that the location is not
physical. Otherwise as I understand it the URI in location could resolve to
something which describes a location, which could be confusing.

Does this seem reasonable. Is there a better suggestion for marking up non
spacial events?

Regards
 Jeremy