How to identify the real production date of milk

Generally, there will be a production date on the milk packaging (that is for consumers ). There is also a dark sign consisting of English letters and numbers, which is the real date of milk production. So how can we identify the company's dark signs to understand the real production date of commodity milk? Generally printed on the packaging of Milk: production date: 080510hdc8h, where:
Production date: 080510 (for consumers;
Code: hdc8h, which doesn't mean anything. In fact, this is the real date of milk production.

The code here indicates the following content:
The first English letter represents the year: industry rules A: 01 years B: 02 years C: 03 years D: 04 years E: 05 years and so on H: 08 years... (in some cases, the year is omitted and only months and days are displayed ). The second English letter represents the month: industry rules A: January B: February C: March D: April E: 05, and so on E: May .. k: November L: December. The third English letter and number represents the date: the first day of the industry plus a: A1, A2, A3, A4, A5, A6, A7, A8, A9; before December 19, 1 was changed to B: B0, B1, B2, B3, B4, B5, B6, B7, B8, and B9. Before December 29, 2 was changed to C: C0, C1, c2, C3, C4, C5, C6, C7, C8, C9; change 3 to D: D0, D1 before 30-31 ).
Therefore: hdc8 stands for April 28, which indicates that although the printed milk on the package is the production date: 080510, the actual production date of the milk is April 28, and the difference is 12 days.
Another example is the production date of 070601 (shown to consumers)
Code: geb4 indicates that the actual production date is actually May 14.