As a publisher you have the possibility to add a sub ID to the links of Daisycon. This allows you as a publisher to make further analyzes about the generated transaction(s).
Some publishers provide data from their (website) users in the sub ID, or use an anonymous parameter that they can (re) trace personal data via their own systems.
If you provide information as a publisher in the sub ID that can be traced back to personal data, you must comply with the rules of the GDPR. Daisycon has a standard processor agreement that sets out the rules that you as publishers must comply with.