Main methods used to predict functional annotations in GO
You can refer the IEA documentation maintained by GO consortium to get an idea about the automatically assigned evidence codes using IEA. Also please note that IEA is different from Computational Analysis Evidence Codes


ISS: Inferred from Sequence or Structural Similarity 
ISO: Inferred from Sequence Orthology 
ISA: Inferred from Sequence Alignment 
ISM: Inferred from Sequence Model 
IGC: Inferred from Genomic Context 
IBA: Inferred from Biological aspect of Ancestor 
IBD: Inferred from Biological aspect of Descendant 
IKR: Inferred from Key Residues 
IRD: Inferred from Rapid Divergence 
RCA: inferred from Reviewed Computational Analysis