MA: Representing Mei An

Supervisor and issuing unit: National Safety Mark for Mining Products;

Location of use: Underground coal mine

KA： Representing Kuang An

Supervisor and Issuing Unit: Office of Safety Signs for Mining Products

Location of use: Non coal mines.

In addition, KY is the general type used for mining, which is used in non gas areas of coal mines and some areas of low gas mines or non coal mines.