I understand that a single gene can be attributed to different gene ontology term. But it's not clear what are the criterions used to add a gene to a gene ontology term. I could also not find any guidelines in the 'DAVID' webpage on how they are doing it or neither any publication. If anyone knows a good publication I can refer to, it will be of great help.

Also, do they take gene that have causal evidences? or even those that have correlative evidences from databases and literature. I am not clear how it works. Thanks!