Document third-party Service_International use, both allocated and defacto. Document brokenness.
Cerilica chunk was allocated decades ago. Defacto usage is even older. As per Allocation’s advice.
It appears that this header is not where detailed API documentation of Service_International goes (why not tho). I’d happily document my 25ish subreasons if only to prevent anyone coining new subreasons for the same purpose (which it seems IS a role for this file).