1.Areas with a special regime of navigation are periodically closed. The time during which these areas are closed for navigation should be broadcasted in the form of PRIP not less than 3 days before the closure of the area and repeated at each regular scheduled time until the opening of the area for navigation. When declaring an area to be closed for navigation, all vessels and floating craft are strictly prohibited to enter it, and vessels in the area are required to leave the area before a time specified in the PRIP.
2.Mean sea level for the period 1940-1955 is 28.0 m below the Kronshtadt gauge zero point. Updated depth corrections are daily broadcasted in hydrometeorological information (METEO). In order to determine the actual depths for the day of navigation, charted depths should be updated using the indicated correction with a corresponding sign.