just a simple link with parameters
<a href="http://domainame.com/?bla=ble&bli=blo">hey!</a>
would make the w3c validator jump two errors, one for the equeal (=) and one for the and (&)
Error Line 1, Column 43: reference to entity "bli" for which no system identifier could be generated
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.
Info Line 1, Column 39: entity was defined here
How can i write them and get 0 errors/warnings?
The equal sign throws no errors. Replace the
&with&like so: