According to the interpretation of Ci Hai, "bam" means the transliteration of English mark, and the Chinese pinyin of "bam" recorded in Shuo Wen Jie Zi is "mà". "Trademark" means "trademark" and "brand" in Cantonese. It can also be used as a "shipping mark", which refers to a mark marked with words, figures and marks on the packaging of goods to distinguish one batch of goods from another. Its manifestations are: batch number, package number, etc. In tea trade, it refers to the name of tea expressed by numbers or numbers supplemented by words, which is also commonly known as "tea code". The symbol of Pu 'er tea is the name of Pu 'er tea in digital form. 1976, Yunnan Tea Company regulates the export of Pu 'er tea logo number:

Cake tea is represented by 4 digits.

The first two are the years when this tea formula was successfully developed, the third is the grade of the main raw materials of the original tea, and the fourth is the number of the tea factory (such as Kunming 1, Menghai 2, Xiaguan 3, Pu 'er 4), such as 7542, 758 1, 86 13, etc. For example, the objective interpretation of 7542 is: 1975 successfully developed formula, and Pu 'er tea produced by Menghai Tea Factory, with 4-grade tea cyanine as the main raw material, is pressed by Yunnan big-leaf sun-dried green tea.

Loose tea is represented by 5 digits.

The first two are the years when this tea formula was successfully developed, the third and fourth are the grades of the main raw materials of raw tea, and the last one is the serial number of the tea factory (such as Kunming 1, Menghai 2 and Xiaguan 3), such as 7807 1, 79562 and 46563.