in reply to Why does back-buttoning to a cgi script-output page yield 'Page expired'?

The post above is correct. To the best of my knowledge, most web browsers do not cash anything that is not an image or a web page by default unless you specify in the header negotiation otherwise. Most web servers do no header negotiation if it is not an html or a image. You'll have to put in the header negotiation yourself. Typically setting the expires tag works. If you are using CGI...
print $query->header(-expires=>'+3d');
If that doesn't force the caching, you'll have to use the Cache-Control header request specified here