The data base I've built is much more complex, with plugins, java, GDT to control external medical devices, etc... I am an autodicact, but of course not a filemaker professional.
Thank you very much for your clarifications and for the time you took to answer. I had understood the mechanism and as you saw identified the problem, but I was not sure that this was a normal filemaker behaviour, as usually scripts do not interrupt other scripts. Now it is clear ;-))
Regards