What do the small three links between Xiamen and Jinzhou refer to?

Refers to the maritime navigation between Kinmen, Matsu, Penghu and Fujian coastal areas such as Xiamen and Quanzhou. It was opened in January 2001, allowing the mainland to unilaterally agree to allow people in the coastal areas of Xiamen and Quanzhou to pass through relatives and friends in the Kinmen and Ma areas or Travel agencies apply to travel to the Kinmen and Ma areas for tourism, business, family visits or funerals; a certain number of mainland compatriots will be allowed to visit Kinmen and Matsu every year, with a maximum stay of no more than seven days.