For the purposes of this Chapter :
(a) personalised security data means personalised data provided to a payment service user by the payment service provider for authentication purposes ;
b) A unique identifier means a combination of letters, numbers or symbols indicated to the payment service user by the payment service provider, which the payment service user must provide in order to allow, alternatively or cumulatively, the certain identification of the other payment service user and his payment account for the payment transaction;
c) A payment instrument means, alternatively or cumulatively, any personalised device and set of procedures agreed between the payment service user and the payment service provider and used to give a payment order;
d) A business day is a day on which the payer’s payment service provider or the payee’s payment service provider carries out an activity enabling payment transactions to be executed;
e) Authentication means a procedure enabling the payment service provider to verify the identity of a payment service user or the validity of the use of a specific payment instrument, including the use of the user’s personalised security data;
f) Strong customer authentication means authentication based on the use of two or more elements belonging to the categories “knowledge” (something that only the user knows), “possession” (something that only the user has) and “inherence” (something that the user is) and which are independent in the sense that the compromise of one does not call into question the reliability of the others, and which is designed in such a way as to protect the confidentiality of the authentication data;
g) Sensitive payment data means data, including personalised security data, that is likely to be used to commit fraud. With regard to the activities of payment service providers providing the payment initiation service and payment service providers providing the account information service, the name of the account holder and the account number shall not constitute sensitive payment data;
h) A group means the whole formed by a company and those it controls within the meaning of Article L. 233-16 of the Commercial Code or institutions within the meaning of Articles 4, 5, 6 and 7 of Delegated Regulation (EU) No 241/2014 of the European Commission which are linked to each other by a relationship within the meaning of Article 10(1) or Article 113(6) or (7) of Regulation (EU) No 575/2013.