Fig. 3From: GLUE: a flexible software system for virus sequence dataThe object structure of an example alignment tree. The constrained Alignment at the root represents an entire virus species. Two child Alignments represent established clades: genotypes 3 and 4. Genotype 3 is further subdivided into two subtypes, 3a and 3b. Each constrained Alignment has a constraining ReferenceSequence. Within each Alignment node there are various AlignmentMember objects, each one records the pairwise homology between the member Sequence and the constraining ReferenceSequence. The alignment tree invariant requires for example that the constraining ReferenceSequence of subtype 3a is also a member of its parent, genotype 3Back to article page