Potential Issue: When Does Applicability Apply to Key SpaceDetermination?

The processing order question has come up quite a few times before, and I
know that there are differences in current implementations. This means that
results may vary today, which is a known issue, and is one reason that
about 4 years ago there was already pressure to create a distinct
"Processing specification" that controlled things like the order in which
different core pieces of DITA were implemented. For example - filtering,
conref resolution, pulling of content into