Form within Tabbar with submit button outside tabbar

I would like to have a form within a tabbar and a submit button outside the tabbar. How can I submit the values in the form WITHIN the tabbar (or access these values from outside the tabbar) on the same page?

If tabbar uses default or ajax based mode - the form is part of page and can be accessed directly

<form name=“a1”…


If tabbar uses iframes form can be accessed as


where id - id of tab in which form loaded