Hi rybtsov,
out of the box that is not possible and do you really want to restrict your
resources entering actual data based on pre-decessors? My take on this is as
follow: You may have planned to only start on a task after the first task is
completed, but you may have actually started working on the second task. Why
wouldnt I as a PM not want to know about it? You will always have variances
between planning and actual tracking. What you should analyse is the gap
between planning and actual tracking so that you can incorporate "real life"
into your planning ( e.g. Lessons Learned).
So to make a long answer short, you will not be able to achieve this out of
the box. If you REALLY REALLY want to do this ( which I strongly recommend
not to) then you could custom develop something ( based on event handlers)
which could prevent entering actual data before the pre-decessor is
completed, but once again, I do not believe that this is a good solution. It
restricts your users unnecesessarily
Hope this helps