validator error: considers "&c=" as html entity when not(?)

Hello www-validator team and list members,

I'm writing to ask about the W3C HTML Validator error
in classifying the following URL as invalid since it contains
a key "c" with a value consisting of "=" characters,
in a GET request. The URL is:
http://mailhide.recaptcha.net/d?k=0144KkHhqYi5eqAOnsUshuOg==&c=9bFP_BxDd-edCpRQmjqwnKmdksWCXUXAeCGJbrNw-P4=

This is a mailhide ReCAPTCHA URL to prevent spam. However,
when such a URL is used in a page, the W3C validator classifies
the page as invalid HTML 4.01, and gives the following err msgs:

--------
The most common cause of this error is unencoded ampersands in URLs

cannot generate system identifier for general entity "c".

general entity "c" not defined and no default entity.

reference to entity "c" for which no system identifier could be
generated.

--------

Please could you help resolve the error.

Thanks,
Sanjay.

Received on Tuesday, 17 July 2007 18:14:35 UTC