19.7.2016 EN Official Journal of the European Union L 194/3 (11) When identifying operators in the water transport sector, Member States should take into account existing and future international codes and guidelines developed in particular by the International Maritime Organisation, with a view to providing individual maritime operators with a coherent approach. (12) Regulation and supervision in the sectors of banking and financial market infrastructures is highly harmonised at Union level, through the use of primary and secondary Union law and standards developed together with the European supervisory authorities. Within the banking union, the application and the supervision of those requirements are ensured by the single supervisory mechanism. For Member States that are not part of the banking union, this is ensured by the relevant banking regulators of Member States. In other areas of financial sector regulation, the European System of Financial Supervision also ensures a high degree of commonality and convergence in supervisory practices. The European Securities Markets Authority also plays a direct supervision role for certain entities, namely credit-rating agencies and trade repositories. (13) Operational risk is a crucial part of prudential regulation and supervision in the sectors of banking and financial market infrastructures. It covers all operations including the security, integrity and resilience of network and information systems. The requirements in respect of those systems, which often exceed the requirements provided for under this Directive, are set out in a number of Union legal acts, including: rules on access to the activity of credit institutions and the prudential supervision of credit institutions and investment firms, and rules on prudential requirements for credit institutions and investment firms, which include requirements concerning operational risk; rules on markets in financial instruments, which include requirements concerning risk assessment for investment firms and for regulated markets; rules on OTC derivatives, central counterparties and trade repositories, which include requirements concerning operational risk for central counterparties and trade repositories; and rules on improving securities settlement in the Union and on central securities depositories, which include requirements concerning operational risk. Furthermore, requirements for notification of incidents are part of normal supervisory practice in the financial sector and are often included in supervisory manuals. Member States should consider those rules and requirements in their application of lex specialis. (14) As noted by the European Central Bank in its opinion of 25 July 2014 (1), this Directive does not affect the regime under Union law for the Eurosystem's oversight of payment and settlement systems. It would be appropriate for the authorities responsible for such oversight to exchange experiences on matters concerning security of network and information systems with the competent authorities under this Directive. The same con­ sideration applies to non-euro area members of the European System of Central Banks exercising such oversight of payment and settlement systems on the basis of national laws and regulations. (15) An online marketplace allows consumers and traders to conclude online sales or service contracts with traders, and is the final destination for the conclusion of those contracts. It should not cover online services that serve only as an intermediary to third-party services through which a contract can ultimately be concluded. It should therefore not cover online services that compare the price of particular products or services from different traders, and then redirect the user to the preferred trader to purchase the product. Computing services provided by the online marketplace may include processing of transactions, aggregations of data or profiling of users. Application stores, which operate as online stores enabling the digital distribution of applications or software programmes from third parties, are to be understood as being a type of online marketplace. (16) An online search engine allows the user to perform searches of, in principle, all websites on the basis of a query on any subject. It may alternatively be focused on websites in a particular language. The definition of an online search engine provided in this Directive should not cover search functions that are limited to the content of a specific website, irrespective of whether the search function is provided by an external search engine. Neither should it cover online services that compare the price of particular products or services from different traders, and then redirect the user to the preferred trader to purchase the product. (17) Cloud computing services span a wide range of activities that can be delivered according to different models. For the purposes of this Directive, the term ‘cloud computing services’ covers services that allow access to a scalable and elastic pool of shareable computing resources. Those computing resources include resources such as networks, servers or other infrastructure, storage, applications and services. The term ‘scalable’ refers to computing resources that are flexibly allocated by the cloud service provider, irrespective of the geographical location of the resources, in order to handle fluctuations in demand. The term ‘elastic pool’ is used to describe those computing resources that are provisioned and released according to demand in order to rapidly increase (1) OJ C 352, 7.10.2014, p. 4.