# File lib/locale/tag/common.rb, line 43
      def self.parse(tag)
        if tag =~ /\APOSIX\Z/  # This is the special case of POSIX locale but match this regexp.
          nil
        elsif tag =~ TAG_RE
          lang, script, region, subtag = $1, $2, $3, $4
          variants = subtag.scan(/(^|[-_])#{VARIANT}(?=([-_]|$))/i).collect{|v| v[1]}

          ret = self.new(lang, script, region, variants)
          ret.tag = tag
          ret
        else
          nil
        end
      end