Imagine you want to test different variables (i.e. creative type, medium), Flowcodes give you the ability to track direct attribution using multiple codes.
For example, if you want to figure out which marketing material works better, you could add Flowcode 1 to flyers, and Flowcode 2 to postcards. Based on the data provided in the My Codes section, you will be able to see which medium performed better. If you only used one code for both creatives, you would not be able to differentiate between performance.