This arises out of a Council list discussion which followed an attempt to implement [feature-requests:#460] by overriding the att.global definition of @rend in the
<list>. This caused problems with DTD generation, and a simpler approach was used, but Lou suggested in the discussion that these three attributes form a natural class.
I think there is a good case for this. Where one is used, the others are also likely to be used (especially with @rend and @rendition); and conversely, a simple born-digital document might not have any need for any of them. It also makes sense to document them together.