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.“

„The recently developed Wo Dui process (渥堆) pioneered by both the Menghai and Kunming Tea Factories has created a new type of pu-erh tea of which some traditionalists dispute the legitimacy. This process involves an accelerated fermentation into "ripe" Shou Cha (熟茶) which is then sold loose or pressed in various shapes.“