Directive (EU) 2019/882 on the accessibility requirements for products and services (AA), provides that the information disclosed by providers of consumer banking services to persons with disabilities in the European Union must be understandable (the understandability rule), a rule that is especially relevant to access barriers related to neurodiversity. Understandability is an open-textured term which, in the multilayered and pluralistic context of financial services regulation, gives rise to ambiguity as to its scope of application. It is not clear, prima facie, whether the understandability rule merely applies to (1) disclosures required under the AA (the narrow application), or also (2) disclosures regulated by other EU Directives applicable to consumer banking services (e.g., Directive 2023/2225 on consumer credits), and (3) contractual documentation provided in accordance with these EU Directives. This article undertakes this interpretation exercise and concludes that the rule should be applied narrowly, on the basis of established EU interpretation methods (grammar, teleological, systemic and comparative), analysis of the contrast between the AA and its regulatory context, and general regulatory principles.