What is the code for sister reunion among American immigrants?

The application procedures for American relatives to immigrate vary according to the location of relatives: one is the situation of overseas relatives, and the other is the situation of American relatives. In either case, American citizens or permanent residents need to submit immigration applications for them first. After the application is approved, relatives can obtain permanent resident status by applying for entry immigrant visas from American embassies and consulates abroad, or applying for adjustment of their status in China.