# TalonOne::ReferralConstraints ## Properties 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, zero, or negative. | [optional] **usage_limit** | **Integer** | The number of times a referral code can be used. `0` means no limit but any campaign usage limits will still apply. | [optional] ## Code Sample ```ruby require 'TalonOne' instance = TalonOne::ReferralConstraints.new(start_date: 2020-11-10T23:00Z, expiry_date: 2021-11-10T23:00Z, usage_limit: 1) ```