Annotation of X. laevis gene expression in the Phenote tool with the XAO. Images of a Nieuwkoop-Faber stage 25 embryo from the XDB3 in situ gene expression database (top) show pax8 expression in the developing pronephros (arrowheads), information that can easily be captured with the ontology-aware Phenote application. The XAO provides a controlled vocabulary for recording stage and anatomical information in the Phenote interface (drop-down menus, at left), while a separate ontology is used for assertions of evidence; data is recorded in a spreadsheet-like panel (bottom-left). The term viewer at right displays information about the current anatomy selection ("pronephric mesenchyme") including its unique XAO identifier, synonyms and definition, relationships to other types in the ontology, and the stage range during which it exists during development. Related types are hyperlinked to give annotators the ability to rapidly browse the ontology for contextual information or to seek a more appropriate item with which to populate an annotation.