To the group, My last message got some how garbeled, so here it comes again:
Dear Jeff, The specification is certainly an improvement in EMC. For screening purposes a metal cabinet need not be earthed. For Common mode emission reduction, a metal cabinet is often used as earth. These are 2 functions that in the case of high level HF-currents become to conflict, due to the imperfect conduction properties of an average cabinet. Voltage difference between fi. left and right side of the cabinet easily flow on cable screenings attached to these points.