Specifies the universally unique ID (UUID) of the item.
Required for library, dispinterface, interface, and coclass. Optional for struct, enum, union, module, and typedef.
The uuidval is a 16-byte value using hexadecimal digits in the following format: 12345678-1234-1234-1234-123456789ABC. This value is returned in the TypeAttr structure retrieved by ITypeInfo::GetTypeAttr.