I interpret that as meaning all cracks, including crater cracks, are not allowed. Regardless of where it is located on a weld, a crack could propagate and make a small problem into a larger one.

Whether a crater crack is likely to propagate or not is a different matter. I've seen crater cracks on existing welds many years old that did not seem to cause any problem. And other welds had started to tear, so it depends on the stress path through the weld. But the best insurance is to allow no cracks at at all, as the code tells us.

Chet Guilford

I agree with all of the previous posts, additionaly a crater crack is a crack; therefore, it is not allowed.

One other comment I'll share that a mentor of mine gave me about cracks was, "Have you ever seen a crack get smaller all by itself?"