Protein domain structures comparison in the ternary relation context. Domains d1w0pa2 (Sialidase with SCOP “Family” Id. b.29.1.8), d1uaia_ (Polyguluronate lyase with SCOP “Family” Id. b.29.1.18) and d1j1ta_ (Alginate lyase with SCOP “Family” Id. b.29.1.8) are respectively figured in gray, white and black. (Top) 73 amino acids long mapped parts of (d1uaia_, d1w0pa2) pairwise alignment, (Bottom) 75 amino acids long mapped parts of (d1uaia_, d1j1ta_) pairwise alignment, and (Middle) 35 amino acids long mapped parts of d1uaia_ common to both pairwise alignments. (Left) mapped parts are represented by boxes along the domain sequence and no-mapped parts are represented by a line. (Right) mapped parts are represented by a stylized ribbon according to its secondary structure, and non-mapped parts are represented with a thin licorice. For the ternary point of view (middle), only the domain common to the two pairwise alignments is represented (d1uaia). In the 3D structures, the blocks mapped in the two alignments are shown in white, the blocks mapped only in the top alignment (d1uaia_, d1w0pa2) are shown in gray and the blocks mapped only in the bottom alignment (d1uaia_, d1j1ta_) are shown in black.