Not the way I exactly understand it ..... but at any rate, yes the agreement doesn't qualify categories precisely, but it does explain how "current mileage" affects the vehicle value (and it tells you calculate the current mileage figure back from today's mileage).
I agree, it's far from ironclad, but should be good enough for most owners anywhere between 15-25K km /year .... 20K being the average 0 base.
Schedule E of the proposed agreement tells us how the mileage for Sept 2015 is calculated but that clearly only applies to cars in the "highest" mileage category.
"For those vehicles whose Current Mileage places them in the highest mileage CBB Wholesale Category, their Vehicle Value will be further determined by establishing by calculation their mileage as of September 18, 2015."
For other cars the applicable (yet vague) description of how vehicle value is determined is in the Long Form Notice, Question J
"CBB uses mileage to determine vehicle categories, which in turn are used to determine vehicle values. Your vehicle’s category at the time of your Buyback will be used to determine your Vehicle Value based upon CBB vehicle values frozen as of September 18, 2015."
Edit: BTW The photo shots of the CBB pages indicated that the base mileage per year is 24,000 km (not 20,000). That's a good thing if it is applied in the settlement.