The first and second categories of Tik Tok are: women's clothing, skin care products, household items, 3C ornaments, pet products, etc. Recommend the first choice, especially household items for family life, such as magic bowl cloth, temperature-controlled hair dryer, and other deadly special household items.

Some of them are the first and second representatives of the first level, the third and fourth representatives of the second level, and so on. The national standard GB 635-87 "National Classification and Code of Industrial and Agricultural Products (Materials)" adopts hierarchical coding. The whole coding structure is divided into four layers and consists of 8-bit codes, in which the first and second bits are the first level (representing categories).

According to the hierarchical order of commodity categories in the classification system, the corresponding numerical codes are given in turn. Hierarchical coding method is mainly used in line classification system. The symbol X stands for code from left to right. The first number represents the first-level category, the second number represents the second-level category, and so on.

Therefore, we can clearly reflect the logical relationship between classification levels with the structure of the code. The third and fourth places are the second level (representing the middle category); The fifth and sixth places are the third level (representing subclasses); The seventh and eighth places are the fourth level (representing varieties or groups).