1. A method performed by a computer with an input means, the method comprising the steps of: (a) storing an attribute identifier, an attribute-specific procedure identifier and an attribute type identifier in an attribute table entry in an attribute table; (b) storing the attribute type identifier, a type-specific procedure identifier and a parent type identifier in a first type table entry in a type table; (c) storing the parent type identifier as a second attribute type identifier and a parent type-specific procedure identifier as a second typespecific procedure identifier in a second type table entry in the type table; (d) executing an application program that obtains data entered by a user via the input means; and (e) executing a separate program upon determining that the data entered by the user in step (d) is an attribute having the attribute identifier stored in the attribute table, the execution of the separate program including the steps of: (e1) locating the attribute identifier in the attribute table; (e2) determining the attribute type identifier stored in the attribute table entry in the attribute table that stores the attribute identifier located in step (e1); (e3) determining the parent type identifier in the first type table entry that stores the attribute type identifier; (e4) executing a parent type-specific procedure identified by the parent type-specific procedure identifier stored as the second type-specific procedure identifier in the second type table entry that stores the parent type identifier determined in step (e3) as the second attribute type identifier; (e5) executing a type-specific procedure identified by the typespecific procedure identifier stored in the first type table entry that stores the attribute type identifier determined in step (e2); and (e6) executing an attribute-specific procedure identified by the attribute-specific procedure identifier stored in the attribute table entry in the attribute table that stores the attibute identifier located in step (e1).