Final Completion Variance - What is this??

Our company operates on a FIFO cost basis and we noticed several jobs with a transaction type of "Final completion variance."  We are familiar with job close variance and period close variance, but we have never seen this variance type and were wondering (a) what it is and (b) what initiated it.
Also, what also seems unusual is that this job is in a completed status (never been closed) and the amount of the final completion variance shows up in the Variances relieved column of the WIP Value Summary.  I thought variances were only relieved when the jobs are closed.