Important Notice: This draft 4^th edition of S-23 was developed during the 1980’s. It was submitted to IHO Member States in 1986, but never received their approval. It is a working document only.

The 1986 draft 4th edition of S-23 was organized in regional chapters as in the table below.

• Chapter	Area
  HEADINGS
  CHAPTER 1	NORTH ALTANTIC OCEAN
  CHAPTER 2	BALTIC SEA
  CHAPTER 3	MEDITERRANEAN REGION
  CHAPTER 4	SOUTH ATLANTIC OCEAN
  CHAPTER 5	INDIAN OCEAN
  CHAPTER 6	SOUTH CHINA & EASTERN ARCHIPELAGIC SEAS
  CHAPTER 7	NORTH PACIFIC OCEAN
  CHAPTER 8	SOUTH PACIFIC OCEAN
  CHAPTER 9	ARCTIC OCEAN