The core of the PIPs data model is the episode. As explained above this is not the broadcast or the media asset but the more platonic grouping of media assets. I’ve heard this described in many ways from assets / broadcasts with the same “editorial intent” to assets / broadcasts telling the same “story”. So for example the Today Programme is a 3 hour broadcast on FM but a 2.5 hour broadcast on LW (the last 30 minutes make way for Yesterday in Parliament) but they’re recognisably the same episode. Or an episode of Casualty might have a BSL version and a non-BSL version but they’re recognisably the same episode. Or an episode of Merlin might get recut to be suitable for broadcast on CBBC but it’s recognisably the same episode / tells the same story. In theory at least (although not to my knowledge in practice) a Prom concert might be simulcast on Radio 3 and BBC Four so would be two media assets (one with moving pictures, one without) grouped into a single episode.