"Clarification on what a 'Round of Fire' is?" Topic

On p.47 of SP2 it says:

Light Infantry in hard cover ignore the first kill in any round of fire to reflect their better training.

Does a 'round of fire' refer to all the fire taking place in a turn, or every time a Group or Formation fires? It seems that, were it the latter, Light Infantry would be nigh-unkillable in hard cover except against a substantial number of other skirmishers. (Well, with my luck, anyway.)

Yes, better get more than one kill, or lots of Fatigue, or Roll good in fistacuffe.

The term "round of fire" is used in three places in the rules, pages 13, 29 & 47. From its use I think it refers to any round of fire from any unit. So if a formation of three groups fires at a Light Infantry unit of two groups and gets three Kills, two on one and one on the other group, the first kill rolled for is ignored(negated). If another unit fires on the LI later that turn, the first Kill is again ignored. So I think a "round of Fire" is per unit not per Group. (i.e. you don't ignore the first Kill on each Group, just the first one on the Unit/Formation.) Otherwise the LI would be nigh-unkillable in hard cover.

Thanks for your help! Presumably then this would also apply to the bow and arrow rules suggested here?