Weighted citations is an indirect assessment mechanism that is employed by DAS.
Weighted citation is a reference to a specific contribution which is weighted by two properties: 1. weight of citation set by referencing contribution author(s), which basically means how important and valuable this referenced contribution is on the author(s) opinion; 1. SCI of the referencing contribution
Weighted citations influence final SCI of a contribution in a way that the more heavy-weighted citations (considering both citation weight set by referencing author(s) and SCI of referencing contribution) a contribution have - the more SCI it will additionally receive from each of those citations.
Weighted citations can include multiple reference levels, and is only limited with requirements for specific use-case or discipline.