check_encoding

# File lib/rexml/encoding.rb, line 57
    def check_encoding str
      # We have to recognize UTF-16, LSB UTF-16, and UTF-8
      if str[0] == 0xfe && str[1] == 0xff
        str[0,2] = ""
        return UTF_16
      elsif str[0] == 0xff && str[1] == 0xfe
        str[0,2] = ""
        return UNILE
      end
      str =~ /^\s*<\?xml\s+version\s*=\s*(['"]).*?\1\s+encoding\s*=\s*(["'])(.*?)\2/um
      return $3.upcase if $3
      return UTF_8
    end