# File lib/rd/rd2html-lib.rb, line 299
    def apply_to_Index(element, content)
      tmp = []
      element.each do |i|
        tmp.push(i) if i.is_a?(String)
      end
      key = meta_char_escape(tmp.join(""))
      if @index.has_key?(key)
        # warning?
        %Q[<!-- Index, but conflict -->#{content.join("")}<!-- Index end -->]
      else
        num = @index[key] = @index.size
        anchor = a_name("index", num)
        %Q[<a name="#{anchor}" id="#{anchor}">#{content.join("")}</a>]
      end
    end