w3.org web site have html error

1. google search http-equiv charset
http://www.google.cn/search?hl=zh-CN&source=hp&q=http-equiv+charset&btnG=Google+%E6%90%9C%E7%B4%A2&aq=f&oq=

2. in google search result ,open http://www.w3.org/International/O-charset

3. copy the page source

4. http://validator.w3.org   Validate by direct input
Result: 21 Errors, 22 warning(s)

  Line 159, Column 96: general entity "btnG" not defined and no  
default entity
…ogle.cn/search?q=http-equiv+charset&btnG=Google+%E6%90%9C 
%E7%B4%A2&hl=zh-CN&c
✉

This is usually a cascading error caused by a an undefined entity  
reference or use of an unencoded ampersand (&) in an URL or body text.  
See the previous message for further details.



find by html validator for firefox   (https://addons.mozilla.org/addon/249 
)
Example:

wrong:
<a href="http://www.domain.com/cgi?x=123&y=456">
right:
<a href="http://www.domain.com/cgi?x=123&amp;y=456">
Solution:

Replace "&" with "&amp;".


ps: on  http://www.w3.org/Consortium/contact   ,I don't know who  
should I contact if I find web site html error.