required and submission

https://www.w3.org/community/xformsusers/wiki/XForms_2.0#The_required_Property

5.3.4 The required Property
This property describes whether a value is required before the instance  
data can be submitted.

This property indicates whether the instance data node must be non-empty  
before a submission of the instance data can occur. A value is non-empty  
if it would have a length greater than zero if converted to string.

(Also in XForms 1.1)

And yet, I find nothing in submission processing that enforces this!

And furthermore, I would expect we should have a submission attribute  
required="false" that allows you to submit regardless of 'required'  
processing.

Steven