Mike, thanks for that.
Your message, however, seems geared only to "heavy" classification - any idea what the deal is with say....a PA28 behind a Gulfstream V, a Citation X or a Hawker, for example.
If, as I suspect, they are being classed as 'no vortex threat to the light aircraft departing immediately behind', then why still the warning to another PA28 that is still on a one mile final.