I understood. Now for me to understand very basic way about transaction fee and withdrawal. Does the transaction fee vary depending on the crypto I am operating and the withdrawal rate also varies? And to make a withdrawal from Bancor, do I have to have Ether or BNT in my wallet or not?
Transaction and withdrawal fees do, indeed, fluctuate relative to the activity in the market. Though it's worth mentioning these fees aren't Bancor's ones but gas fees due to congestion in the Ethereum network. Also, in order to make a withdrawal you just need to have any of the supported currencies in your wallet.