Vitamin D is not an authentic vitamin; it is a corticosteroid hormone.
The EFAs (Linoleic, 18:2/w6, and Alpha-Linolenic Acid, 18:3/w3) are functional vitamins; their derivatives (GLA/w6, EPA/w3, DHA/w3) are not (but are beneficial, like many non-essential amino acids).
Cholecalciferol is made in the skin from D precursor in response to full-spectrum light. The EFA derivatives are made through an ascending enzymatic series, starting with Delta-6-Desaturase.
Anything that can be made in a healthy body from a healthful diet should not be called a vitamin.
However, the term, vitamin, is largely political, controlled by the FDA, USDA, et al.
Scientists tried to have the Wulzen Anti-Stiffness (anti-arthritis) Factor declared a vitamin in the 1940s, but the USDA quashed it, because they did not want to admit that the lucrative Pasteurization process (fees, fines) destroyed a valuable nutrient in raw milk fat.
The Wulzen Factor is another corticosteroid hormone, but a plant-source one (from green grass, hence a benefit of “grass fed”).
The Weston Price X-Factor, also rich in grass-fed milk fat, is another authentic vitamin - one finally recognized as K2.
The AMA and Big Pharma do not profit from healthy people who do not need them. The Federal agencies are on their side, not ours.
Follow the money. Always.