ZTC classes or "Zero-Textbook-Cost" classes are classes that have chosen a textbook that can be accessed freely online (such as an OER textbook) as their required textbook, or another no-cost option for the their textbook (such as no required textbook).
You can now search for courses that are using a zero-textbook-cost option in the class schedule! Watch the short video below that demonstrates how to search a "ZTC" class.