effectively optional self-reference in group redefinition

The definition of group redefinition attempts to require variants of
extension and restriction.  The extension variant falls between two
stools -- it allows pre-extension, and doesn't actually require
extension at all, since the self-reference can be wrapped inside a
<choice> or optional <sequence>.  We should do more or less -- I
favour less, i.e. make it _just_ like extension for types.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/

Received on Friday, 16 November 2001 05:22:08 UTC