Default Interfaces 

The default interface of a package works as a substitute for the package or its contents in a dependency control list. It can either be implicitly created by the package check when the contents of a non-encapsulated package needs to be referred to in a dependency control list or it can be explicitly specified, as a normal package interface, when a non-encapsulated package should be converted to an encapsulated package.

An implicit default interface is created implicitly by the package check and exposes all contents of its package. It is, in most cases, not closed. Access to the exposed objects may be subject to certain sanctions (errors, warnings) depending on the package's encapsulation level.

An explicit default interface is one of its package's normal package interfaces that is chosen to replace the implicit default interface. Usually, parts of it or even the whole interface will be deprecated.

All clients that refer to the default interface will be "re-directed" to the configured package interface. An explicit default interface is optional, that is, packages don't need to specify it. In particular, newly created packages do not have a default interface.

·        Not Encapsulated Packages: Implicit Default interface

·        Weakly Encapsulated: Implicit or Explicit default interface. In either case, the default interface is deprecated when it is referred to by the DCL of a client package.

·        Encapsulated packages: There may be an explicit or empty default interface. The default interface of an encapsulated package must be closed. The default interface is deprecated when it is referred to by the DCL of a client package.