[MIT-Scheme-devel] Why does URL:ENCODE-STRING not encode & and ; etc.?

[craven]

Hello fellow Schemers!

I may misunderstand things here, but isn't URL:ENCODE-STRING meant to
propertly encode characters that are special to urls? Examples would be
=, & and ; (which should all be encoded). However, 

> (url:encode-string "a=b&b=c;c=d") 

just echoes that string literally ("a=b&b=c;c=d") without any encoding.
This is by design, as these characters are explicitly added to
URL:CHAR-SET:UNESCAPED in runtime/url.scm. 

Is this implementation based on a different understanding of
url-encoding? What am I missing here? I'm trying to use it to url-encode
the name and value of cookies for HTTP, which necessarily means it must
encode at least = and ; correctly.

Thanks for any help!

Peter