Form element dependencies

Hello,

With HTML5 form validation comes a possibility to validate user written data without any server intervention (Before actually sending the whole form data) or custom client-side scripting. However, currently there is no predefined functionality in the markup or Javascript for form element dependencies. And with 'dependencies', I mean an element's validity/availability being triggered by another element's validity. Has this been considered at any point? 

Please redirect me to the right mailing list if this not the right place for this kind of discussion.

Cheers,