Looking at the example in the DMG for cover on a grid map they aren't very clear, well in some ways they are but in others no. The examples aren't the best either since they use a large creature as the target which leaves me with some questions for two equal size foes.
OK so on page 250 of the DMG it shows cover for square maps. On the three quarters cover it shows the lines brushing the one corner of the cover but not going through and then hitting a corner of the foe while the rest of the lines pass through the cover so the shooter has 3/4 cover. Well if they were both medium, and say you had a setup like this. (I don't think I can clip the pic from the DMG and post it due to IP and all that jazz...)
A B C *see attachment
All in a straight line on a 1' grid map with A 2' from B and C who are adjacent to each other. So going from a corner on A to a corner on C you are going to have 2 though B and 2 running along the side of B but not though it. In Line of Sight it mentions a line touches but in cover it says blocked and it has a line as OK when it touches the edge of a square occupied by cover. So does A have line of sight on C according to the rules and does C only have 1/2 cover or are all those lines blocked and no LoS?
I know I'll get 'You are the DM do what you want' since these are variant rules anyway and I know that and will, but I was wondering what the intent of the rules is.