Thanks for the information. However, that didn't answer my query above. Could you post your sample qvw? You have to understand how maxstring() works; what the field type you are applying this expression to get the expected output. If you want one quarter back value by simply subtracting 1, then your field has to be created in the script accordingly; and that is probably a dual field and not just as a string. If you can share your sample app, we may help you suggesting a solution fits for your case.
Yours is text field. Ideally this should have been created in the script as a dual field. However, to deal with this in the UI there would be many ways like using complex if..then..else along with string functions. I used another way of parsing the date and then to apply date functions..
That mostly like means, your sample data is not really representative sample of your actual data. And without knowing that (how your actual data is), it would be very hard for us to keep guessing and suggesting a probable solution. I would rather suggest you to provide more information about your data, or get the logic what I suggested above and try to solve yourself from there onward.
