External References Tables

Ensembl supports the link of external database entries to internal objects. This is done on translation and transcript objects, and may be done on genes in the future. An external entry is described in the xref table and the database it comes from in external_db. Any synonyms for the external entry are stored in external_synonym.

Links to Ensembl are in the object_xref table. Some links need additional information (attached to the link and not the external entry). Derived GO identifiers are qualified by the way they were derived (go_xref.linkage_type). External links that are derived from aligned peptides are annotated with the alignment details in identity_xref.