Chart correction N31/23 — chart 44186
44186 3Ed. 09/03/16 LAST NM N20/23 N31/23 Add Light Q(6) + L Fl W 15s to buoy 59°34′27″N 18°40′26″E Light Q(3) W 10s to buoy 59°40′58″N 18°59′36″E Light Q(3) W 10s to buoy 59°40′42″N 18°58′41″E Light QR to buoy 59°40′41″N 18°59′02″E (968(17671)23 Norrkoping)
Source: NGA U.S. Notice to Mariners · edition: 3Ed. 09/03/16
Reference information — always verify against official Notices to Mariners before navigation.