'CPU used when call started' vs 'CPU used by this session'

Hello

I have recently read somewhere that the statistics (from v$sesstat/mystat/sysstat)
'CPU used when call started' and
'CPU used by this session' are (nearly) equivalent
but that 'CPU used when call started' should be used instead of 'CPU used by this session' because the latter is buggy.

Now, is that true?

And if so, why does Oracle have two statistics for the same thing.

If not so, what is the difference.

I have played a bit with it and indeed, the values seem to be identical for both statistics.

Thanks,
Rene

-- 
  Rene Nyffenegger
  http://www.adp-gmbh.ch/