From catalog/rfc3986-uri.abnf rule: scheme

Definition

scheme = ALPHA *(ALPHA / DIGIT / "+" / "-" / ".")

Info

Rulename
scheme
Dependencies
ALPHA, DIGIT, scheme
Used Builtins
ALPHA, DIGIT

Alphabet

Translations

Railroad Diagram

scheme ALPHA ALPHA DIGIT + - .

Swift Regular Expression

[A-Za-z][+\--.0-9A-Za-z]*

POSIX Extended Regular Expression

[A-Za-z][+\--.0-9A-Za-z]*