The Hierarchy of Relationship Types in GenomicDataRelationships.xsd. The GenomicDataRelationships schema (gdr, see additional file 4: GenomicDataRelationships.xsd) specifies an inheritance of xsd:complexTypes rooted on 'RelationshipType'. Textual definitions of these Relationships are provided by inline xsd:annotaions. A global Element is defined for each Type, with the document structure of the root Element 'Relationship' reflecting the inheritance pattern of the Types, which is shown here. Thus a 'SequenceSimilarity' is a type of 'Similarity' is a type of 'Relationship'.