Hi Eleanor, The component types are designed to specify, in a generic fashion, the manner in which the component may link (or not link if the component is a non-polymer component). The goal of this scheme was to economize the specification of polymeric bonding, representing only a discrete number of linkage types. If you feel that the enumeration of this item is incomplete please advise us of any extensions that you think are necessary. Regards, John ****************************************************************** John Westbrook Rutgers, The State University of New Jersey Department of Chemistry 610 Taylor Road Piscataway, NJ 08854-8087 e-mail: jwest@ndb.rutgers.edu Ph: (732) 445-4290 Fax: (732) 445-4320 ******************************************************************