RestrictIO uses the JSON format for storing the ban entries. The file is located at
It is only useful to edit current values as it is fairly simple (i.e. if you don't have enough space for your text in the GUI or console). Adding new criterias/actions/etc. needs you to know the field names (the JSON is a serialization of the data structure in the core). For that you have to look into the source code.
If you have edited your file you can reload it with