MST configuration revision number
When implementing Spanning Tree Protocol (STP) using MST, the MST revision number is one of the attributesused to identify a unique MST region. It is a construct that is intended to be used by administrators to ensure that the MST configuration is the same on all switches in the region.
The idea is that every time you make a change to the MST configuration on a switch, you manually increment the revision number by one on that switch. In order to get the rest of the topology to sync up to that change, you must go into each switch in the region, and increment the revision number by one. This is a manual process and can be cumbersome especially if you have many switches.