user46240: My understanding is that a transaction is a transfer of value between Bitcoin wallets that gets later included in the block chain. So a Bitcoin transaction is used only once in my understanding.

user30668: What is spent it's not the transaction itself, but the outputs the transaction has created. A transaction can have multiple outputs with different bitcoin amount hold on each one. 
Therefore, a transaction can be "used", in the sense you expressed it, as many times as outputs it has. 

46240: <p>My understanding is that a transaction is a transfer of value between Bitcoin wallets that gets later included in the block chain. So a Bitcoin transaction is used only once in my understanding.</p>
 30668: <p>What is spent it's not the transaction itself, but the outputs the transaction has created. A transaction can have multiple outputs with different bitcoin amount hold on each one. </p>

<p>Therefore, a transaction can be "used", in the sense you expressed it, as many times as outputs it has. </p>
