We have a search centric view of the world, hence Event --> Query ID is required. However, even in our Chorus demo, we collect events before a search has been performed, so there is no query. Do we say that Query ID is REQUIRED? or do we say that prior to a search, the Query ID is ""?

This is a gap between the reality of how we are using UBI in the demo versus the definition of the specification here!. This would become a problem if we actually enforced the specification format when collecting data in any of the implementations of UBI that are extant!