XHTML validation script uri with parameters

[mariotto]

Hi everybody.
I'm building a web site with code XHTML (structure), CSS (presentation) and asp3 (no .net) scripts (dynamic data).

I encountered a trouble in validating xhtml pages with URI with parameters. Ex.

<a href=&quot;www.pippo.com?param1=a[ampersend]param2=b&quot; etc.>

because w3c validator don't recognize parameters as valid entries:

Error: general entity "para" not defined and no default entity
Error: reference not terminated by refc delimiter

How can I write a correct script uri with parameters? :-?

Note: I wrote [ampersend] to significate "&" because in preview it was impossible to see "&" in my ex. uri.

Help me, please

MArio