From catalog/rfc9110-http.abnf rule: year

Definition

year = 4DIGIT

    

Info

Rulename
year
Dependencies
DIGIT, year
Used Builtins
DIGIT

Alphabet

Translations

Railroad Diagram

year DIGIT DIGIT DIGIT DIGIT

ECMAScript/JavaScript Regular Expression Literal

/^[0-9]{4}$/

Swift Regular Expression

[0-9]{4}

POSIX Extended Regular Expression

[0-9]{4}