When the FU finishes the execution of an instruction and the result is ready for forwarding and buffering, the instruction is said to complete.
Instruction completion is out of program order.
During completion the reservation station is freed and the state of the execution is noted in the reorder buffer.
The state of the reorder buffer entry can denote an interrupt occurrence.
The instruction can be completed and still be speculatively assigned, which is also monitored in the reorder buffer.