Table 1.

A summary of the terms used in common between the CATH and SCOP structure classification databases.

CATH	SCOP	Description
Class	Class	Hierarchy separated by gross structural differences (e.g. secondary structure content)
Architecture	–	Similar general organization of secondary structures within 3D space
Topology (fold)	Fold	Structural similarity without clear evidence of evolutionary similarity
Homologous superfamily	Superfamily	Structural and functional features suggest a common evolutionary origin (often despite low sequence similarity)
–	Family	Clusters domains with clear evolutionary relationship (usually including significant sequence similarity)
FunFam	–	Clusters domains with functional similarity