language_tags::GRANDFATHERED_IRREGULAR

pub const GRANDFATHERED_IRREGULAR: [&'static str; 17] = [
    "en-GB-oed",
    "i-ami",
    "i-bnn",
    "i-default",
    "i-enochian",
    "i-hak",
    "i-klingon",
    "i-lux",
    "i-mingo",
    "i-navajo",
    "i-pwn",
    "i-tao",
    "i-tay",
    "i-tsu",
    "sgn-BE-FR",
    "sgn-BE-NL",
    "sgn-CH-DE"]

Contains the 17 irregular old language tags not matching the standard grammer of tags.