Provisional Slot Allocation for AFC Club Competitions 2019 and 2020

With completion of 2017 AFC club competitions today, 2017 AFC Club Competitions Ranking should be published by AFC soon. This ranking will be used by AFC to determine which member associations (MA) are eligible for AFC Champions League and AFC Cup in the 2019 and 2020 seasons. How are the slots allocated? Are the slot allocation for each MA fixed?