>What's the diference between optimist and pessimist ?
>I read help but dind't understand
Optmistic locks records just before trying to save them. It is called optimistic because even when you start editing the record it does not lock it, it waits until you try to save it (and it hopes that it will succed locking and saving.)

On the other side, Pessimistic locks records as soon as you start editing them. It does not care if you will save or discard your changes, it will lock the record right away to prevent other user from getting to it.


>When do I have to use command: tablerevert ( ) ?
Let's say the user make some changes to the record on the screen and then they decide they don't want to save their changes. They hit "cancel" and your program will issue a TableRevert() to make sure those changes are gone.