Puerh History - Pu-erh.Net

„Yunnan Tea Company standardized the trade number for Pu Erh Tea in 1976 for the purpose of export. Each bingcha has 4 digits: the first 2 digits indicate the manufacturing year, the third digit indicates the leaf grade, the last digit indicates the tea factory (e.g. Kun-Ming 1, Meng-Hai 2, Xia-Guan 3, Pu Erh 4). The loose-leaf tea has 5 digits with the third and fourth indicating the class level of raw materials. Examples of early trade numbers for Puerh Tea are 7452, 7562, 7572, 75671, 76563.“

„Bitterness
Broad leaf variety (Sinenesis Assamica) is high in natural constituents; polyphenols, caffeine,theine, etc. A particularly bitter flavour is a special characteristic of the Broad leaf variety, but it is important that it transforms quickly and does not linger. This is a mark of good quality Puer. NB there is a sub-variety in Yunnan - Var. ku cha which has different characteristics and does not transform in the same way.“