as with many other things, there are more than one possible solution. My favorite is using MonYear as a dual. This is the field MonYear has a text (for representation) and an integer value (for calculation). Take a look into my load-script, there I defined the field and a Variable called vactMonYear. With those you can easily compare and calculate like I did in the straight table chart. And it is also usable in Set Analysis.
32619.AutoDate.qvw 148.5 K