15 Sep
1999
15 Sep
'99
9:14 p.m.
Only 256 characters is _guaranteed_, but you seem to be able to get away with quite a bit more.
My only other data point is that Internet Explorer is unhappy after about 2000 characters. My current project is likely to be pushing this limit, so I would be interested if anyone has seen anything lower. http://www.zope.org/Members/htrd/urllen contains a quick test.
IE 4.5 on the Mac seemed to go out a little bit longer than IE 5 on the PC. Apache hushed me up somewhere above 5000.