The second option in the Rules tab of your data garden are the rules that apply to Mutating records.
When creating a rule under this subsection, the rule will be executed at the exact moment the record status changes. For example, when a respondent fills out the questionnaire, the status of the records will mutate from New, to Active and eventually Completed. At the moment the record status mutates, the system will check the rules that are present in the Mutating records section and execute them.
The added value of creating rules in this section, is the ability to specifically target records at the moment they are updated. So when a questionnaire is filled out and a new result comes in, your info is up to date.
By using the rules in this section, you also ensure that already completed records (historic data) are not included. Since their status will not change anymore, the rules will not be executed on these records.
You have hired a new regional manager, responsible for the Region North. You only want the new results to be in the name of your new manager. The old records remain in the name of the former regional manager.
However, the records for this region are already automatically created by the connection to your CRM system, and they therefore still have the name of the former manager applied to them. To make sure that any new results that come into your dashboard are updated to the new regional manager, you use the Mutating records section.
By adding the rule to this section, any record that changes status, gets updated with the name of your new manager. The old records are not affected, since they don't change status anymore.
This is just one example, of course the possibilities are endless. The most important criteria for using this section of rules, is that you only want to impact records of which the status (New, Active, Completed) changes.
Pro tip: you can select specific records and manually change their status in the dataview. This will enable you to create a rule and apply it to a specific set of records by manually updating their status. Once your done, simply deactivate or delete the rule to prevent other records from being impacted, and your records are up to date!