One-code-only account is the main account set up by China Clearing for each investor, which is used to record the identity information of investors and securities assets. As a sub-account of investors' investment transactions, the securities account establishes the relationship between the one-code account and the sub-account. Sub-accounts include A-share accounts, B-share accounts, share transfer system accounts, closed-end fund accounts and other securities accounts established by China Clearing according to business needs. The same investor can only apply for opening a one-code account.