How does complex fields in special fields work?

In CF7 you can define special fields in read data action. You can choose two options: 'Decode JSON' or 'Complex field'.
How does the option 'Complex field' work? How can I use this?
​
I'm trying to figure out if I can use this option to transform data from a db to other value. For examle:
- 0 -> Zero, 1-> One, etc.
​
Hopes somes can explain. Thanks.
​
Regards, Hans

No, it does not work like that, you can set a new field name in the data set and define a value for it:
​
data path: Model.new_filed
new value: {var:Model.field1}/{var:Model.field2}, some string!