Originally Posted by jrbearus

MX11A is a relatively new grade when they decided to break MX11 into two parts, right in the middle.

Based on the data thatI have seen, it ranges from 5 to 12 years for the progression from MX 11A to MX 10. For those from the time before MX 11A was introduced, it was as short as 5 to 6 years; i.e. MX 11 to MX 10.

CEP plays a major role!