^((?P<grandfathered>(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)|(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang))|((?P<language>([A-Za-z]{2,3}(-(?P<extlang>[A-Za-z]{3}(-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})(-(?P<script>[A-Za-z]{4}))?(-(?P<region>[A-Za-z]{2}|[0-9]{3}))?(-(?P<variant>[A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*(-(?P<extension>[0-9A-WY-Za-wy-z](-[A-Za-z0-9]{2,8})+))*(-(?P<privateUse_opt1>x(-[A-Za-z0-9]{1,8})+))?)|(?P<privateUse_opt2>x(-[A-Za-z0-9]{1,8})+))$