请问这种map是怎么实现的
网址如下
http://www.esg.montana.edu/gl/gl.html
HTML如下
<HTML>
<HEAD>
<TITLE>Graphical Locater</TITLE>
</HEAD>
<BODY>
<H1>Graphical Locater</H1>
Select a location for a more detailed map (USA only).<BR>
<A HREF="/gl/usa.map">
<IMG ISMAP SRC="img/usa1d.gif"></A>
<HR>
<A HREF="/gl/gl0.map"><IMG ISMAP SRC="/gl/img/gl0.gif"></A><BR>
6 NOV 1997, last updated on 2 DEC 1999,
<A HREF="/dlg/dlg.html">D.L. Gustafson</A><BR>
<A HREF="mailto:dlg@rapid/msu.montana.edu">dlg@rapid.msu.montana.edu</A><BR>
</BODY>
</HTML>
map文件如下
http://www.esg.montana.edu/gl/usa.map
请求如下
http://www.esg.montana.edu/gl/usa.map?200,297
请问这种是怎么实现的?
跟area元素有什么区别