| Name | Type | Description | Notes |
|---|---|---|---|
| start_date | datetime | Timestamp at which point the referral code becomes valid. | [optional] |
| expiry_date | datetime | Expiration date of the referral code. Referral never expires if this is omitted. | [optional] |
| usage_limit | int | The number of times a referral code can be used. `0` means no limit but any campaign usage limits will still apply. | [optional] |