 Measures of local compactness in proteins have been used in many of the early methods of domain assignment and in several of the more recent methods.One of the first algorithms used a Cα-Cα distance map together with a hierarchical clustering routine that considered proteins as several small segments, 10 residues in length.The initial segments were clustered one after another based on inter-segment distances; segments with the shortest distances were clustered and considered as single segments thereafter.