"subordinated" comes from the English word subordinated, which means subordinate and in a secondary position, and is generally used to indicate the repayment order of debts in bank terminology. Subordinated debt means that the creditor's right to the debtor's assets is inferior to that of other creditors. That is to say, only after the debtor has paid off the creditor's rights of other creditors, if there is any surplus property, can it be used to pay off the creditor's rights of secondary creditors. Therefore, subordinated debt is actually a kind of debt whose right to compensation is constrained, and the risk of subordinated debt to creditors is greater than that of ordinary debt. However, for the debtor (that is, the bank that issues debt or bonds), this kind of debt with constrained rights can give him a guarantee close to equity capital. That is, his nature is between ordinary debt and equity capital. This is why long-term subordinated debt can only be counted as secondary capital, but not as core capital.