When I enter code 46 in batch mode and then enter the NOL carryforward absorbed that year it does clear the diagnostic. I have to do this in batch mode for each year because if I hit Ctrl-W again I can't see where the entry is or where it needs to be for the next year. No matter what I do I cannot see the detail entry area below the grid.

It turns out I only get the not valid code message if I try to delete code 46 (which I can not do even though the code was mistakenly entered twice on one year).

The tax returns with this diagnostic look fine now. Thanks again for your help during this busy time!