Final answer:
The Air Force materials are classified into Classified and Unclassified categories, with classified materials requiring special clearance due to national security sensitivity.
Step-by-step explanation:
The Air Force materials are classified into two main categories: Classified and Unclassified. Classified materials encompass information that could compromise national security if disclosed without authorization and thus is limited to individuals with the necessary clearance. On the other hand, Unclassified materials are not sensitive to national security and can be accessed by the general public without any need for special permissions.