When linking to a non-HTML file, such as Excel, Word or Acrobat, make it evident, by including a small icon next to the link.

• 已访问的链接颜色应该不同，这样访问者可以了解已经浏览过哪些内容（未访问的链接最好使用紫色或者其它比较柔和的颜色），