2.1.50 [W3C-HTML52] Section 4.10.17.3. Association of controls and forms

V0190: The form attribute cannot be used to override the nearest ancestor form element

The specification states:

 ... Association of controls and forms
     ...
     A form-associated element is, by default, associated with its nearest ancestor form 
     element (as described below), but, if it is reassociateable, may have a form 
     attribute specified to override this.

EdgeHTML Mode

The form attribute cannot be used to override the nearest ancestor form element.