What does the number in the lower left corner of the windshield mean?

[EllieMarie]

The number in the lower left corner of the windshield indicates the production date of the glass. There is usually a number and several small black dots in the last or second-to-last row, which represent the production date. The number stands for the last digit of the production year, while the small black dots indicate the production month. Some glass panels have the black dots before the number, while others have them after the number. If the black dots are before the number, subtract the number of dots from 7 to get the production month. If the black dots are after the number, subtract the number of dots from 13 to determine the production month. Some glass panels also have additional larger black dots after the production year and month, which specify the week of the month. For example, 5 dots represent the first week, 4 dots represent the second week, and so on.