Mapping of the domain definitions of the two hierarchies. An overlap threshold > 0 is used, i.e. all domains which share at least one residue are mapped onto each other. The SCOP row shows the number of CATH domains mapped onto a single SCOP domain, while the CATH row describes the number of SCOP domains mapped onto one domain defined in CATH. A single domain in SCOP may be partitioned into up to 6 domains in CATH. Overall, about 20'000 (19'641) out of about 70'000 (68'892) SCOP domains map more than one CATH domain while about 11'500 (11'513) out of about 80'000 (79'783) CATH single domains map to more than one SCOP domain.