Outside envelope is a duty of test pilot to understand what is going on and not for a stupid pilot as me.
The flight envelope which is approved for use will have been generated by the test pilots exceeding it. For example, Mmo is M0.82. This means the test pilots will have exceeded it, probably by a considerable margin, and by applying appropriate factors to their test flights, the manufacturers have used M0.82 for operations.
What it does not mean is that the wings will come off at M0.83.