The original mandate of X3J11 was to “codify common existing practice”. The published Rationale goes on to describe a number of relevant criteria, including •

The original mandate of X3J11 was to “codify common existing practice”. The published Rationale goes on to describe a number of relevant criteria, including • Existing code is important, existing implementations are not. • Avoid “quiet changes.” • Trust the programmer. • Keep the language small and simple. • Make it fast, even if it is not guaranteed to be portable. In pre-ANSI C, and C89 C interpreted in line with the Rationale, if you wrote ‘+’, the expectation was that you'd get the target machine's ‘add’ instruction, no more and no less. It might overflow, it might not; it might crash or hang your machine on overflow or trap values — but that is all your problem, not the language's or compiler's. The ANSI invention of ‘undefined behaviour’ can be considered a good-faith attempt to codify things like this, but botching it was one of the two great failures of C89. I worked on a commercial compiler at the time, and I'm confident no one thought of C89 as a license to screw the customer.