Each placeholder has a replacement type that tells MyDataMerge what kind of content you want to merge in. For each replacement type you can create one or more setups to work with to handle simple or complex scenarios with conditions.
 Setup selection button
 Process chain button (off)
Standard mode (= Proces chain turned OFF)
In the standard mode (process chain turned off ), the selected setup  is taken into account for export – no matter if you have more than one setup in the list.
When should i use standard mode?
Use standard mode with simple setups and completely filled databases (without missing fields).
Process chain mode (= Proces chain turned ON)
In the process chain mode (process chain turned on ), every setup in the list  is taken into account. See process chain for more details.
When should i use process chain mode?
Use process chain mode if you need to have different behaviors or different content for different data. Or use it to catch missing fields and place alternative content. See process chain for more details.