# File lib/rd/rd2html-lib.rb, line 354
    def apply_to_Footnote(element, content)
      num = get_footnote_num(element)
      raise ArgumentError, "[BUG?] #{element} is not registered." unless num
      
      add_foottext(num, content)
      anchor = a_name("footmark", num)
      href = a_name("foottext", num)
      %Q|<a name="#{anchor}" id="#{anchor}" | +
        %Q|href="##{href}"><sup><small>| +
      %Q|*#{num}</small></sup></a>|
    end