Ah, THE DELTA: it is the difference between the max oil film tickness and minimum oil film tickness. So the ring closing its gap 6,28 times the Delta of film tickness. Now, If the (distance or thickness) between the bore and ring gap changes 1 micron, the gap on the ring tips will close 6,28 microns.
Now I've got what Jetronic was trying to say ...
Thanks!