If you are using Server Side Rewarding you might already be familiar with custom parameters you can associate with a given Rewarded ad completion.

Starting from DT FairBid SDK 3.11.0 the same SDK API has been added to the Interstitial ad format as a way to enrich the User Level Reporting.

This is how you can use it:

Interstitial

Dictionary<string, string> customParameters = new Dictionary<string, string>();
customParameters.Add("myCustomKey", "myCustomValue");
customParameters.Add("anotherCustomKey", "anotherCustomValue");
ShowOptions options = new ShowOptions(customParameters);
Interstitial.Show("placementID", options);

Rewarded

Dictionary<string, string> customParameters = new Dictionary<string, string>();
customParameters.Add("myCustomKey", "myCustomValue");
customParameters.Add("anotherCustomKey", "anotherCustomValue");
RewardedOptions rewardedOptions = new RewardedOptions(
            customParameters);
Rewarded.Show("placementID", rewardedOptions);