https://en.wikipedia.org/wiki/Out-of-order_execution

The way the instructions are ordered in the original computer code is known as program order, in the processor they are handled in data order, the order in which the data, operands, become available in the processor's registers.

Re-order buffer A re-order buffer (ROB) is used in a Tomasulo algorithm for out-of-order instruction execution. It allows instructions to be committed in-order.