[css3-writing-modes] what are the Sv and Sh categories in Appendix C

>From CSS3 Writing Modes, Appendix C: Vertical Typesetting Synthesis:
http://dev.w3.org/csswg/css3-writing-modes/#vertical-typesetting-details

> For vertical typesetting, using [[!UTR50]] and the rules below,
> characters are assigned into one of five categories:
> ...
>
> sideways (Sv)
>     These characters are sideways (rotated 90° clockwise) in both
>     ‘upright-right’ and ‘upright’ text orientations. 
> 
> non-native (Sh)
>     These characters are sideways in ‘upright-right’ orientation and
>     upright in ‘upright’ orientation. 

I can't find a draft of the UTR-50 that defines these categories.  Is
this based on a private discussion or is this a separate proposal of
someone?

Also, the link to the current draft UTR-50 is not set up correctly in
the bibliography file, such the references in the editor's draft
appear as [[!UTR-50]].

Regards,

John Daggett