# File lib_wpm/wpm.rb, line 392
    def escape_specials(raw_string, mode=:number)
      raw_string.gsub(CHAR_PATTERN) {|utf8|
        case (mode)
        when :number
          '&#' + CHAR_CODE[utf8].to_s + ';'
        when :symbol
          '&' + CHAR_SYMBOL[utf8] + ';'
        else
          raise "internal error: #{mode.inspect}"
        end
      }
    end