Article 170 1.

a rating system shall take into account obligor and transaction risk characteristics;

a rating system shall have an obligor rating scale which reflects exclusively quantification of the risk of obligor default. The obligor rating scale shall have a minimum of 7 grades for non-defaulted obligors and one for defaulted obligors;

an institution shall document the relationship between obligor grades in terms of the level of default risk each grade implies and the criteria used to distinguish that level of default risk;

institutions with portfolios concentrated in a particular market segment and range of default risk shall have enough obligor grades within that range to avoid undue concentrations of obligors in a particular grade. Significant concentrations within a single grade shall be supported by convincing empirical evidence that the obligor grade covers a reasonably narrow PD band and that the default risk posed by all obligors in the grade falls within that band;

to be permitted by the competent authority to use own estimates of LGDs for own funds requirement calculation, a rating system shall incorporate a distinct facility rating scale which exclusively reflects LGD related transaction characteristics. The facility grade definition shall include both a description of how exposures are assigned to the grade and of the criteria used to distinguish the level of risk across grades;

significant concentrations within a single facility grade shall be supported by convincing empirical evidence that the facility grade covers a reasonably narrow LGD band, respectively, and that the risk posed by all exposures in the grade falls within that band.