Announcements that ask you to confirm you read them

Kinds include safety alert, schedule change, site closure and policy change, with normal, high or critical priority and an optional expiry. An emergency notice is always critical, always asks for confirmation and is also emailed. The sender sees how many confirmed and can remind the rest, up to three times a day. Publishing at a later time is not available yet.

Important notices are different from chat, and you know who has seen them.