The OSKit's interfaces are a set of clean, object-oriented interfaces specified in the framework of the Component Object Model (COM), described in Chapter 4. These interfaces are made available through thoroughly commented public C header files, with corresponding documentation in Part ii of this manual. For example, the OSKit provides a ``block I/O'' interface for communication between file systems and disk device drivers, a ``network I/O'' interface for communication between network device drivers and protocol stacks, and a file system interface similar to the ``VFS'' interface in BSD. These interfaces are used and shared by the various OSKit components in order to provide consistency and allow them to be used together easily. The OS developer may additionally use or build on these interfaces in defining the fundamental structure of the client OS, but is not required to do so; alternatively, the developer may simply use them when writing the ``glue'' code necessary to incorporate a particular OSKit component into a new or existing OS environment.