Chapter 16 is the HS classification category for 'Preparations of meat, of fish, of crustaceans, molluscs or other aquatic invertebrates', covering processed (e.g., cooked, cured, smoked, canned, etc.) animal-based foods, but excluding products that are only simply frozen, fresh-chilled, or dried and unprocessed (classified under Chapters 2 and 3). The core of this chapter lies in 'depth of processing' and 'method of preservation', usually involving cooking, mixing, seasoning, or sealed packaging, etc., giving the product the characteristics of being ready for direct consumption or long-term storage. Heading 1604 specifically covers 'Prepared or preserved fish; caviar and caviar substitutes prepared from fish eggs', including whole or in pieces fish that have been cooked, smoked, cured, canned, or otherwise processed, as well as caviar substitutes. However, it excludes fish that are only simply frozen, fresh-chilled, or dried (classified under Chapter 3), and also excludes fish meal, fish products for animal feeding (classified under Chapter 23), or fish oil (classified under Chapter 15). This heading emphasizes that the fish has undergone substantial processing and is usually intended for human consumption. The first 2 digits '16' indicate Chapter 16, i.e., preparations of meat, of fish, of crustaceans, molluscs or other aquatic invertebrates. Digits 3-4 '04' indicate heading 1604, specifically prepared or preserved fish; caviar and caviar substitutes prepared from fish eggs. Digits 5-6 '11' are the subheading, indicating 'Preparations of salmon', i.e., whole or in pieces products made from salmon (Atlantic salmon, chum salmon, etc.), whether or not canned, smoked, cured, or cooked. Therefore, 160411 in full means: prepared or preserved salmon (whole or in pieces), belonging to subheading 11 under heading 4 of Chapter 16. This product is classified under 160411 because it is a whole or in pieces product of salmon that has been prepared or preserved (such as smoked, canned, cured, cooked), meeting the definition of heading 1604 'prepared or preserved fish'. If it were only fresh, chilled, or frozen salmon, it should be classified under Chapter 3 (such as 0302, 0303); if it were salmon caviar, it would be classified under 1604.20; if it were minced salmon or surimi products, it might be classified under 1604.20 or 1604.90. Therefore, the processing method and form are the key to distinction.