When you configure an attribute for an object type, and DRA performs one of the supported operations, that attribute will be updated (stamped) with DRA specific information, including who performed the operation. This causes AD to generate an audit event for that attribute change.
As an example, assume you selected the attribute extensionAttribute1 as your user attribute, and you have AD DS auditing configured. Whenever an AA updates a user, DRA will update the extensionAttribute1 attribute with Event Stamping data. This means that along with the AD DS events for each attribute that the AA updated (e.g. description, name, etc.) there will be an additional AD DS event for the extensionAttribute1 attribute.
Each of these events contain a Correlation ID that is the same for each changed attribute that was changed when the user was updated. This is how applications can associate the Event Stamping data with the other attributes that were updated.