For more complicated fieldtypes, such as Grid, Relationships, or Assets you may need to provide better context for the diff parser to work. Essentially these add-ons use their own tag markup to parse the data, which you need to provide. This setting lets you use an existing snippet file to parse the data. Do not include the channel entries tag inside of these snippets. It is recommended to keep this snippet code a simple as possible and only add what is necessary to view a difference in content. For example do not add superfluous HTML or CSS.