to the letter

Adverb

idiomatic not-comparable

(idiomatic) Literally, exactly, following the rules as written.

Japanese Meaning

文字通り、字義どおりに / 正確に、正しく / 規則や指示に厳密に従う

She followed the contract to the letter, refusing to accept any unofficial amendments.

彼女は契約を条文どおりに守り、非公式の修正を一切受け入れようとしなかった。

Sense（1）

(idiomatic) Literally, exactly, following the rules as written.

You should follow what your boss said to the letter. Otherwise, you'll lose your job.