How many categories of textbooks are there for module leaders to decide for their teaching?

There are three categories of textbooks: Mandatory Textbook, Optional Textbook and Reference Textbook.

• Mandatory textbook is a required book in either print or electronic format for a module that students are obligated to purchase. 
• Optional textbook is a book in print that students can choose to purchase or not.
• A reference textbook is a book in print that is considered additional or recommended reading by academic staff and is only purchased for Library’s collection where it can be offered for loan.