When you use this formula: (ROC(C,260,%)+ROC(C,130,%)+ROC(C,65,%)+ROC(C,22,%))/4 in the Explorer it rejects securities that lack 261 days of data. Is there a way to write something like

if there is at least 261 days of data then (ROC(C,260,%)+ROC(C,130,%)+ROC(C,65,%)+ROC(C,22,%))/4
else if there is at least 131 days of data then (ROC(C,130,%)+ROC(C,65,%)+ROC(C,22,%))/3
else if there is at least 66 days of data then (ROC(C,65,%)+ROC(C,22,%))/2
and so on....

so that short securities would not get rejected?

I tried it and it fails the same way as the underlying function. IsDefined(ROC(CLOSE,260,%)) fails with the message "Error in Column A: Period value out of range in ROC() function." on all securities having 260 days or less and they are rejected.

There are two reasons why this is not a good thing. First, by rejecting the security outright the Explorer prevents me from calculating some other substitute function for the security that would prevent the security from being rejected. Second, it prevents me from using the exploration to get the complete list of all securities in the folder; if I want this result as well, I need to run a separate exploration that has no rejections.

Maybe I am not using the function correctly. Any idea?

Right, isdefined() is useless. But by some miracle, the below works. It returns N/A when the security is less than 261 days and returns the ROC otherwise. Any idea why this works?

M:=Ref(C,0)/Ref(C,-LastValue(Min(260,Cum(1))))-1;

If(Cum(1)<261,0,M);