Classification view in MM02 -to maintain change history(CDHDR/CDPOS)?

Hi,

Please provide me a solution for the following scenario.

I was trying to change the characteristic description and value in classification view in MM02 for a given material number.

I want that whenevr i change any characteristics it should maintain in changes history table(CDHDR/CDPOS).

How to activate this for classification view as currently its not maintaining the history in the tables (CDHDR/CDPOS).

Its very urgent.....