I'm only quoting the rules Bloggsy. ( I don't see why ATC can't just ask for what they want using plain English either )
Aust ATC will either say "cancel SID maintain runway heading clear for takeoff" or "cancel SID assigned heading *** clear for takeoff"
In 30 years of IFR in Oz I've never been instructed to fly *** track after takeoff.
Oz ATC will be aware of the wind and will allow for the drift in their heading instructions to achieve the separation results they want.
So as I said above In Oz, Canada and the good ol US of A RWY HDG means HDG.