v_RecentRangeTo =Max([Year-Month] In Block)
v_RecentRangeToMonth =ToNumber(Right([v_RecentRangeTo];2))
v_RecentRangeToYear =ToNumber(Left([v_RecentRangeTo];4))
v_RecentRangeFromMonth =FormatNumber(If([v_RecentRangeToMonth]=12;1;[v_RecentRangeToMonth]+1);"00")
v_RecentRangeFromYear =FormatNumber(If([v_RecentRangeToMonth]=12;[v_RecentRangeToYear];[v_RecentRangeToYear]-1);"0000")
v_RecentRangeFrom =[v_RecentRangeFromYear]+""+[v_RecentRangeFromMonth]
v_PreviousRangeToMonth =Right([v_RecentRangeTo];2)
v_PreviousRangeToYear =FormatNumber(If([v_RecentRangeToMonth]=12;[v_RecentRangeToYear]-1;[v_RecentRangeToYear]-2);"0000")
v_PreviousRangeTo =[v_PreviousRangeToYea]+""+[v_PreviousRangeToMonth]
v_PreviousRangeFromMonth =FormatNumber(If([v_PreviousRangeToMonth]=12;1;[v_PreviousRangeToMonth]+1);"00")
v_PreviousRangeFromYear =FormatNumber(If([v_PreviousRangeToMonth]=12;[v_PreviousRangeToYear];[v_PreviousRangeToYear]-1);"0000")
v_PreviousRangeFrom =[v_PreviousRangeFromYear]+""+[v_PreviousRangeFromMonth]
Finally,
v_Recent 12 Months = Sum([Amount] where ([Year-Month] >= [v_RecentRangeFrom] And [Year-Month] <= [v_RecentRangeTo]))
v_Previous 12 Months = Sum([Amount] where ([Year-Month] >= [v_PreviousRangeFrom] And [Year-Month] <= [v_PreviousRangeTo]))