I think it's pretty clear isn't it?
Unfortunately no, it isn't. If you look at the way what we call SOG is calculated (and some details have been posted above) you will realise that strictly it is not what the ICAO document describes, however, the difference is irrelevant for air traffic services (the document's subject matter).
Kudos to the OP for posting what must be the most interesting question I've read here so far this year. Although aware of it, I'd never consciously thought about it.