The number of ‘unique users’ as regards ‘active business users’ is to be determined, where applicable, at the account level with each distinct business account associated with the use of a core platform service provided by the undertaking constituting one unique business user of that respective core platform service. If the notion of ‘business account’ does not apply to a given core platform service, the relevant undertaking providing core platform services shall determine the number of unique business users by referring to the relevant undertaking.