You know, it’s nice and all that multistep logic is possible in a custom field calculation, but don’t you think it might be NICER to make it possible to debug something like this

IIf([Imported Actual Finish]<>projdatevalue("NA"),100,(IIf([Imported Actual Start]=projdatevalue("NA"),0,(IIf([Imported Expected Finish]=projdatevalue("NA"),0,(IIf([Imported Actual Start]>=[Imported Expected Finish],0,(IIf([Imported Remaining Duration]<0,0,((ProjDateDiff([Imported Actual Start],[Imported Expected Finish])*2/3)-[Imported Remaining Duration]*60*8)/((ProjDateDiff([Imported Actual Start],[Imported Expected Finish])*2/3))*100)))))))))

without resorting to external editors? I mean, just some basic paren matching would save an awful goddamn lot of time…