>Suppose a situation :
>- a header-detail form (1 to many as you wish)
>- detaillines are created with a primary key that is a simple integer, which comes from some counter-table
>- Transactions are used so if the user decides to cancel, the entries can be rolled back
>
>The problem is :
>2 simultanous users can't use this form because the record holding the detailline number (its pimary key) is kept locked during the transaction.
>
>Any suggestions ???

I assume you're keeping the record lock so that you can recover the used primary key number? If this is the case, you should just let them get used and discarded if not saved. Just be sure to make your counter field and PK field long enough to accomodate the larger numbers.

HTH