To reference the types, items, and subprograms that are declared within a package specification, use the dot notation. Example:
To invoke a function from the emp_admin package specification, execute the following SQL statement.
SELECT emp_admin.get_dept_name(10) FROM DUAL;

In the preceding statement, the get_dept_name function declared within the package emp_admin is invoked. The department number is passed as an argument to the function, which will return the name of the department. Here the value returned is ACCOUNTING, which corresponds to department number 10.