According to the v4.0 release notes (#3):
only leaders ( the x0 ) with radios can call arty...x4 unit with a radio it doesn't mean he can contact the artillery only leaders can do that
Does this refer to "spotting" for barrage / bombardment? Does this apply to FO type units?
Secondly, it appears that there can only be one spotter for barrage / bombardment for all artillery, mortar and arial bombardment units.
If that's true, then not all bombardment can be w/in LOS (regardless if there are FO on opposite sides of the theater).