Data Type. A collection of operations, each with a name and a signature defining the number and types of its arguments. application domain A domain whose purpose is to execute an application program. binding An association of a name with some value; in IDC, the local data structures for invoking an operation on an interface. class A set of objects sharing the same implementation. An object is an instance of exactly one class. closure The concrete realisation of an interface. A record containing two pointers, one to an operation table and the other to a state record. concrete type A data type whose structure is explicit. constructor An operation on an interface which causes the creation of an object, and returns the interfaces exported by the object. context A collection of bindings of names to values. context slot A data structure used to hold processor execution state within a domain. ix domain The entity which is activated by the kernel scheduler. Domains can be thought of a..