V17 CLOSING PERIOD BOUNDARY CHECK
TIMEZONE: Asia/Tokyo
INTERVAL: [2026-08-21T00:00:00+09:00, 2026-09-21T00:00:00+09:00)
INCLUDED: B,C
EXCLUDED: A,D
UNKNOWN: U (date missing; do not infer)
INCLUDED_SECONDS: 300
SYNTHETIC ONLY: DO NOT FETCH OR SEND
NOT A LEGAL DEADLINE: NOT AN INVOICE