Ignore some request variables

[Mark Gibson <mark@xxxxxxxxxxxxxxxxxx>]

I'd like to cache searches in a site.  Unfortunately, the site uses 
images as submit buttons - e.g. <input type="image" src="path/to/image" 
... />

Whenever the submit button is clicked, the location of the click on the 
button is sent along with the other input variables.  This makes it 
difficult to cache the search results.  Is there any way to tell squid 
to ignore specific request variables when caching a page?