What does the common "arc" on glasses mean?

ARC is a French company whose full name is Arc international. There is a factory in Nanjing, China. The Arc brands that can be seen in China are: luminarc is called Lemeiya in Chinese, and Arcoroc is called Gono in Chinese. The former is a retail brand, and the latter is a catering brand, but it was screwed up. Later, both channels were basically Lemeiya.