about auto focus. the AFBUFST REG.

Dear  All,

          Now I use the auto focus engine. I can get the auto focus value through AFBUFST, but I don't  know the data format of AFBUFST and the mean of them.

         Anybody tell me? 

        I look the VPFE datesheet several times, but I can't find any information.  Is there any information supply?

      Thanks a lot.

Regard