Is it possible to validate hidden fields?
The use case is an accordion and we want to validate fields in closed sections of the accordion. We are happy to manually trigger validation on the accordion sections - this need not be a generic form-wide solution.
I have achieved this by placing a checkbox on the form, then cheking it and styling it to display:none with JQuery.
I put a Valid if... rule on the checkbox and in the rule I have code to validate other fields on the form. Any validation errors will appear below the hidden checkbox.