Gene_association files of Gene Ontology (GO) annotations for non-rat species such as mouse, human and dog are downloaded from the GO Consortium website (http://www.geneontology.org/). Chinchilla manual GO annotations are retrieved from the RGD database. Annotations with experimental evidence codes (IDA, IMP IPI, IGI, IEP or EXP) in the originating species are automatically assigned to the orthologous rat genes with an evidence code of ISO (Inferred from Sequence Orthology; for more information about GO evidence codes, their meaning and how they are used, go to the GO Consortium evidence code documentation at http://www.geneontology.org/GO.evidence.shtml). The original reference ID for the paper from which the annotation was made in the original species is assigned as the "XREF_SOURCE" and appears in the "Original reference" column of the website display. In addition, the PMID of the original reference is included in the reference column of the GO annotation files available on RGD's ftp site (ftp://ftp.rgd.mcw.edu/pub/data_release/annotated_rgd_objects_by_ontology/ and ftp://ftp.rgd.mcw.edu/pub/data_release/annotated_rgd_objects_by_ontology/with_terms/).