This is partially described in the accompanying text. In addition:

• It shows a typical breaking of the data into A-G, H-M, N-S, and T-Z
• It adds the concept of the data flowing gradually from the employees table to the user process
• It shows intra-operation parallelism for the full table scan and the ORDER BY operation
• It shows the inter-operation parallelism for going between those two inter-operation parallelisms
• The SQL statement is SELECT * FROM employees ORDER BY last_name;