(19)To allow clients and competent authorities to effectively assess whether market data is provided on a RCB, market data providers should disclose all information relevant to the offering of market data in clear and unambiguous terms. That information should enable clients and competent authorities to understand market data policies, including how the level of fees for market data is determined, and should be provided with a uniform content and using a uniform format and terminology. Market data providers should provide the competent authority, upon request, with the information on the total costs of production and dissemination of market data, including a reasonable margin, by using a harmonised format.