The document is a notification from the Coast Guard, part of the Department of Homeland Security, about temporary rules they issued for safety zones, security zones, and special local regulations that became effective and expired primarily between October 2021 and December 2021. These temporary rules were necessary for safety and security but could not be published in the Federal Register in time. Mariners and the public were informed through other methods like Local Notices to Mariners and press releases. The Coast Guard lists these temporary rules periodically to fulfill its obligation of public notification.
Simple Explanation
The Coast Guard made some short-term rules to keep people safe in certain areas, but they didn’t tell everyone about them in the Federal Register in time. So, they used other ways like local news and boat announcements to let people know.