I believe the "if not agreed" is more to do with the Oct to Dec 2019 pricing, where it is related to both Carbonate and Hydroxide pricing (Hydroxide pricing is introduced at this time). If there is a difference between the pricing (one goes lower, one goes higher) then which do you chose?
I believe that is why the statement exists, it favours USD$880 per tonne or the higher value (between Hydroxide and Carbonate) if there is a difference/disagreement between the 2 prices used in the calculation.
A40 Price at posting:
17.0¢ Sentiment: Buy Disclosure: Held