In MEAN WELL's catalog, we see AC and DC at input, what does this mean?

Due to different circuit designs, MEAN WELL power supply's input consists of three types as below:(√2VAC≒VDC)
a.85~264VAC;120~370VDC
b.176~264VAC;250~370VDC
c.85~132VAC/176~264VAC by Switch; 250~370VDC

• In a and b inputs models, power supply can work properly no matter under AC or DC input. Some models need correct connection of input poles, positive pole connects to AC/L; negative pole connects to AC/N. Others may require opposite connection, positive pole to AC/N; negative pole to AC/L. If customers make a wrong connection, the power supply will not be broken. You can just reverse the input poles and power supply will still work.
• In c input models, please make sure that you switch the 115/230V input correctly. If the switch is on the 115V side and the real input is 230V, the power supply will be damaged.