Similarly, the ranking of websites by the providers of online search engines, notably of those websites through which undertakings offer goods and services to consumers, has an important impact on consumer choice and the commercial success of corporate website users. Providers of online search engines should therefore provide a description of the main parameters determining the ranking of all indexed websites and the relative importance of those main parameters as opposed to other parameters, including those of corporate website users as well as other websites. In addition to the characteristics of the goods and services and their relevance for consumers, this description should in the case of online search engines also allow corporate website users to obtain an adequate understanding of whether, and if so how and to what extent, certain design characteristics of the website used, such as their optimisation for display on mobile telecommunications devices, is taken into account. It should also include an explanation of any possibility for corporate website users to actively influence ranking against remuneration, as well as an explanation of the relative effects thereof. In the absence of a contractual relationship between providers of online search engines and corporate website users, that description should be available to the public in an obvious and easily accessible location on the relevant online search engine. Areas of websites that require users to log in or register should not be understood as easily and publicly available in this sense.
To ensure predictability for corporate website users, the description should also be kept up to date, including the possibility that any changes to the main parameters should be made easily identifiable. The existence of an up-to-date description of the main parameters would also benefit users other than corporate website users of the online search engine. In some cases, providers of online search engines can decide to influence the ranking in a specific case or delist a particular website from a ranking based on a third-party notification. Unlike providers of online intermediation services, providers of online search engines cannot, due to the lack of any contractual relationship between the parties, be expected to notify a corporate website user directly of a change in ranking order or a delisting due to a third party notification. Nevertheless, a corporate website user should be able to inspect the contents of the notification that has led to the change in ranking order in a specific case or to delisting of a particular website, by investigating the contents of the notification such as in a publicly accessible online database. That would help to mitigate potential abuses, by competitors, of notifications that could lead to delisting.