(4)Given that Article 4(1) of Regulation (EC) No 1060/2009 permits the use of credit ratings for regulatory purposes by credit institutions and investment firms only if issued by credit rating agencies established in the Union and registered or certified in accordance with that Regulation, the mapping of ECAIs credit assessments should cover credit assessments that comply with the definition of ‘credit rating’ according to point (a) of Article 3(1) of that Regulation. Further, given that by virtue of Article 136 of Regulation (EU) No 575/2013, a mapping is required for all ECAIs, the definition of which includes, by virtue of Article 4(98) of that Regulation also credit ratings produced by central banks exempted from the application of Regulation (EC) No 1060/2009, the mapping of ECAIs rating categories should also cover such credit ratings as well. Regulation (EU) No 575/2013 prevents the use of credit ratings for certain asset classes (such as equity) within the Standardised Approach. Therefore, with regards to assessments for fixed-income collective investment undertakings (CIUs), only those that solely depend on the credit quality of the underlying assets should be covered by the mapping of ECAIs' credit assessments.