Whether an enumerated type has an underlying integer type that is signed or unsigned is not well documented in the compiler manual, and is fairly complicated. In fact, the documentation is wrong for this test case. Given an enumerated type with all non-negative values that fit in "signed int," the compiler will pick "unsigned int" for the underlying type, which is common practice in the industry. The documentation claims that the type chosen will be "signed int." We will be carefully examining enumerated types and the documentation for enumerated types for future releases.