Hi ,
You can achieve this with the help of Formula Variables .
Declare 2 formula variables i.e. 1 for reference characteristics 0CALMONTH_FROM and other for 0CALMONTH_TO processing by replacement path.
In the Replacement path defintion take it "Replace variable with" select "Key".
You can logical Operators to validate the condition i.e. if it less than and falls between the from and to condition.
Hope it helps.
Thanks
Kamal