adverb, noun which may take the genitive case particle 'no'
according to the rules; by the book; legally
Used when an action or situation strictly follows established rules, regulations, or legal requirements. Often implies no deviation or bending of rules.
The referee proceeded with the match according to the rules.
Please apply following the standard procedures.
Compound of ルール (from English 'rule') and 通り (どおり, 'in accordance with').