I am not sure what you mean by system ... but on a weekly base most databases record the links of published papers to the previous literature. When a link is confirmed it counts as a citation.
You have to distinguish though self-citations from third party citations. The first are generated when the authors of a paper reference their previous published work. There is nothing wrong with this, but the current consensus on the citation index DOES NOT consider the self-citations. This of course is logical if one considers that the citation metric is a rather simple value evaluating the academic prestige of a particular researcher or published topic.