A library list is a list of libraries maintained for each user session with the libraries arranged in decreasing order of priority.
Whenever an object is referenced in command without a library, then the system starts checking for the object in all the libraries in the library list.
If the object is found in the first library, then the system picks that object from that first library.
If the object is not found in any library in the library list then the system will throw an error.
