okay-dokey one25six. How about redrawing the diagram with a point B for where the heavy is 6nm from the light and increasing?
A wee point for 3slips, ICAO wake catagories don't apply in the UK obviously enough, and also not in Canada of all places! Let's see... where is ICAO's HQ??? Silly, but there you go. Canadian lights are 5,700kg / 12,500 lbs or less, which is a might confusing coming from the UK where, even with an extra catagory, there are lights which are Canadian mediums.
Cases in point, JS31, B350, D328, C550 and many more.
I just had a look in MANOPS and there's a good digram showing a heavy with a line going out behind it, and aircraft shown going in all directions at a point where wake turbulence separation exists. Section 533 for equally geeky...