CRM 4.0 passing attribute value to an iframe via a url on a form

[Saners]

I’m using CRM 4.0 and I want to pass an attribute value as a parameter to a url in an IFrame. It works fine with the parameter value hardcoded into the url e.g.

the url on the iframe is set to -

http://test/ISV/NewPersonDetails.aspx?PersonNo=999999

However I want to pass the attribute value called ‘new_personnumber’ as a parameter. ‘New_personnumber’ is an attribute on the form where the IFrame is held. I’m not sure of the syntax. I know I have to pass ‘new_personnumber’ as a querystring but not sure how.

Please help!

Many thanks in advance.