menu array item size limit?

[theking@mysecretbase.com]

I have this client who is trying to use swapover images. Trouble is, if the urls are too long they don't work. At some point (unknown at present) the menu can't handle the sheer length of the url.

Here's a sample menu item - its really a real image url, too. Doesn't work. The client's image/swapimage url was of course much shorter (74 characters), but still didn't work.

,"<img src=http://foohbar.org/images/thisis/anabno ... outuep.gif border=0>","index.cfm swapimage=http://foohbar.org/images/thisis/anabno ... ,"About",1

Since we're using swapimages, the problem is magnified.

The above is coming from a system that automatically builds the menu out of a db. Absolute urls are in use so a single admin area can control multiple menu systems kept in multiple folders on the client web site.

Whats the limit that I'm running up against? Is there any chance of lifting it to allow a really long string as above? If I have to I can make mods to allow relative urls via base href settings, but if a simpler fix is available I'd love to hear it. Base HRef settings can bollix up other things, and I'd rather keep menu settings self-contained if possible.
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NOTE ADDED JUNE 4:
I've recommended to the client that they either implement mappings in the web server or just copy their image folders so the admin area and the live areas can both use relative urls, so I think this is solved without an excess of brainpower. Still, I'm curious as to what the limit is.