One slide is a little misleading. It says:
"This is also a duophonic Cal (sic?) object. It describes two "identifically descripted (sic?)" WHATS, occuring at the exact same WHEN in two different WHERES. For example, if Ronald McDonald was to make an appearance in two restaurants at the same time. This can not be described in iCal without using the mechanism of related objects."
The implication is that iCalendar can't do this and is deficient. The use of RELATED-TO property is not an enhancement or add-on to iCalendar. It is an integral part. Hence, iCalendar CAN SUPPORT THIS topology. Where is the beef?
-- Frank