An Account can have up to three Credit Limits, which are debit amounts that the balance of the Account may not exceed. The difference between the actual balance of an Account and the Credit Limit is called the Available balance.
Whether an Account will use one or more Credit Limits is set on Admin, Account Type, Credit Limit page.
Typical uses for Credit Limits are: Revolving Credit Loans, Overdrafts on a Current Account, or a pre-approved Loan amount where the monies are to be drawn over a period of time (perhaps in the case of a property development).
Together with Credit Limits, you can add future withdrawals to the Account. These are taken off the Available Balance so that those funds are not mistakenly paid out to the borrower, creating a situation where the Account is over-lent.