Available money
Your complete balance in any currency is made up of your available balance and your reserved balance.
Available money is any spare money in your account which has not been reserved against either (i) a purchase order posted on the BullionVault order board, (ii) a pending withdrawal or (iii) a transaction still pending settlement, such as an order at the Daily Price set at the London Fix. You can enter a new purchase order to spend your available balance, or a withdrawal to have it sent back to you.
Reserved money
Your reserved balance is the money which is reserved to settle open orders and unsettled deals or withdrawals pending processing.
When you place a purchase order on the order board your available money balance will go down as it is transferred to your reserved balance - where it stays until your order executes or is cancelled.
You can make your reserved money available again by killing open orders.
Available and Reserved Bullion
You also have available and reserved balances of gold, silver and platinum. Your available bullion is any which is not reserved against an open sell order posted on the BullionVault order board or a sale that is pending settlement or is part of an individual bar which has been reserved in your name. You can enter a sell order to sell your available bullion.
You can make some of your reserved bullion balance available again by killing any sell orders open on the BullionVault order board.
Overall balance
For both bullion and cash your overall account balance is unaffected by orders which have not yet executed. Amounts that are available, reserved or pending settlement (if relevant) all contribute towards your overall balance.