## C.12. Extension Objects, Enums, and Typedefs

Expanding on previous discussion, extensions can add values to existing enums; and can add their own commands, enums, typedefs, etc. This is done by adding to vk.xml. All such additions will be included in the vulkan.h header supplied by Khronos.

Note Application developers are encouraged to be careful when using switch statements with Vulkan API enums. This is because extensions can add new values to existing enums. The use of a default: statement, within a switch, may avoid future compilation issues.