I need some help with a formula. I want to create a line item (LINE ITEM B) to check that another line item (LINE ITEM A) only has an entry in one period. The line item that I want to do the check on is a manual input and has a numeric format. I basically want the model to flag an error to tell me if there are values entered in multiple periods in LINE ITEM A (or a value entered in any period other than the one in my view).
My model does not have an 'all periods' field (and I don't want it to) as I'd thought about a formula that checks to see whether the current period in LINE ITEM A is equal to the sum of all periods in LINE ITEM A. I've a feeling that this should be relatively straightforward but I'm struggling currently.
6 years (broken down into months) and yes, a new year will be added every year (but not frequently obviously). I'm currently summing up the 6 FY totals manually in the formula and doing a check on this but it's a bit clunky as the formula will need to be edited manually each year the model is rolled over (admittedly not a big job if it's documented properly).
Although I'm hoping there's some sort of 'NOT CURRENT PERIOD' type formula that'll do it a bit neater, in the absence of the all periods field in this model.