What is the rule of product code on numbers and English letters?

What is the rule of product code on numbers and English letters?

The long-life of Dailywell products, the code rule is from 1 to 8 with different English letters, and we call the “EIGHT SERIES”.
For example, toggle switches are 1 and 2, rocker switches are 3 and 4, slide switches are 5 and 6, and pushbutton switches are 7 and 8. Then, 1,3,5 and 7 are small switch systems, and 2,4,6 and 8 are tiny switch systems.
The letter of M is Dailywell standard type, F is high class standard, A is water proof type, and B is SMT type. The particular are 2U,4U and 8U types are showing tiny switch products.
2TE is water proof of toggle switch, the size is better than 2A series.
5SE is water proof slide switch, the size is as same as 2TE series.

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