There are three types of cash substitution: cash substitution is forbidden (marked as "forbidden"), cash substitution is allowed (marked as "allowed") and cash substitution is required (marked as "required").

prohibiting cash substitution is the origin of ETF subscription and redemption rules, that is, adopting the principle of "barter" can effectively control the transaction cost and tracking error of ETF and ensure the effectiveness of ETF's basic arbitrage mechanism.

allowing cash substitution is generally applicable to stocks that investors cannot buy at the time of subscription due to suspension of trading and other reasons. For the stocks replaced by cash, the fund manager needs to buy them after they resume trading, so the fund company will charge a certain cash premium to the subscribers.

Cash substitution is generally applicable to the constituent stocks that will be eliminated after the adjustment of the underlying index, or the fund company considers it necessary to implement cash substitution for reasons such as protecting the interests of the holders. For stocks that must be replaced by cash, the fund manager will announce a certain amount of cash to be replaced in the list of purchase and redemption, that is, "fixed replacement amount".