Ah, ok Michael!
Thanks.

To use that command (planar), I've selected the base edge loop (by the way, is there a way to select a loop without select all edges one by one?) and then launch the command... I did'nt undestand that you can use it as "cap planar holes" in a solid!
It's a bi-functional command: it closes the planar holes and it creates planar surfaces from edges! Good.

Thanks a lot
Marco