Chart of Accounts - Sub Accounts
The Chart of Accounts needs to make provision for the definition of Sub-accounts aka "child" accounts for any account number. One example would be top level account "800100 - Shareholder Equity", child or sub-accounts "800110 - Equity Shareholder 1", "800120 - Equity Shareholder 2", "800130 - Equity Shareholder 3", etc.
Many accounting systems implement this by defining a "Level" for each account number together with a "Reports To" value for each account number where the top level account is the reporting level account, and each child account MUST select the parent Account number as its "Reports To" value. If no Reports To value is specified, then the account is by default a top level or reporting account.