Looking at a copy of a bomber command plotting chart dated 19 May 1942 I've noticed a number of symbols of an "x" within a circle and letters alongside them. Others, fewer in number, are of a cross of larger size with a number alongside it. The former are also present on the continent with the name of the location alongside e.g. "VITRY". I suspect these are M.F. beacons, including enemy ones and the large crosses are M.F. D/F stations. I have tried to attach part of the chart. I would be interested if anybody can confirm my assumptions or not and also if anyone has any information about the location of RAF M.F. D/F stations at this period.