Attached to a version there might be “publication events”: broadcasts and “ondemands”. A version might have zero, one or many broadcasts. Each of which might be on a different radio network or TV channel (e.g. Eastenders on BBC One and BBC Three). Networks and channels are modelled as “services” in PIPs because there isn’t a common “natural” word so SMEF went with service. And a version might have zero, one or many ondemands which determine if a version is available for iPlayer streaming or download for a given time period, territory, platform etc.