This is possible because any component of executable code or data in file is encapsulated into a secure unit called Object.

Anything available in this system is an object. This provides a common interface to work through them.

This interface allows for standardized commands across different system elements. Each and every object are referenced by a library, under which they reside. Library in IBM i system is also an object. They act as a container for all other objects.There are a set of system libraries supplied by IBM with the machine in OS. Any user created library resides under the system library QSYS.