Blocker Description
Regression in new separator/sequences code.
When the separator is a prefix of the terminator, or any other piece of in-scope terminating markup, then the separator match is preferred to the longest match, and that makes any format that depends on longest-match disambiguation to fail.
The one example we have of this is in VMF's spec scraper.
So we also need a test of this in daffodil-test to have better coverage.