Heading 1506 captures fats and oils from animals not covered by the dedicated headings for bovines, swine, poultry, fish, marine mammals, or wool-bearing animals. Examples include fats from horses, insects, or other specialty sources. The heading is a true residual, so classification here should be confirmed only after ruling out all more specific headings in chapter 15.

The restriction excludes fats that have undergone reactions altering their chemical structure, such as hydrogenation, transesterification, or sulfonation. Refined but structurally intact fats — those that have been filtered, bleached, or deodorized — remain within 1506. Chemically altered animal fats typically move to chapter 15's modified-fat provisions or to chapter 34 or 38 depending on their end use.