(92)In order to avoid any regulatory arbitrage, the rules on securitisation should apply on the basis of the principle of substance over form. To this end, a clear and encompassing definition of securitisation is needed that captures any transaction or scheme whereby the credit risk associated with an exposure or pool of exposures is tranched. An exposure that creates a direct payment obligation for a transaction or scheme used to finance or operate physical assets should not be considered an exposure to a securitisation, even if the transaction or scheme has payment obligations of different seniority.