Yili pure milk has an a after the date.

There is an A after the date of Yili pure milk, which is the origin code. The symbols A and B of Yili pure milk represent the representative letters of milk producing area and marketing area, A represents northwest areas such as Inner Mongolia and Ningxia, A 1 represents Jinchuan, Inner Mongolia, a3 represents Wulanchabu and a5 represents Bayannaoer. B stands for Heilongjiang, Jilin and Liaoning provinces, and Area B will be divided according to different cities.