[NTG-context] startconstants broken

[Hans van der Meer]

Upgrading seems to have broken \startconstants (and probably also  
\startvariables). The code below worked in cont-tmf version 2008-08-05  
but no longer in 2008-10-31:

\startconstants all
	spine:    spine
	% etcetera
\stopconstants
\startvariables all
	% etcetera
\stopvariables

The error is:
! Undefined control sequence.
<argument> \c!spine
                     =\v!none
\xprocesscommaitem #1,#2->\if ,#1
                                  ,\@EA \xprocesscommaitem \else  
\if ]#1\@EAE...
<argument> ...=\v!cd ,\c!spine =\v!none ,\c!state
                                                   =\v!draft ,\c! 
output =\v!p...

\xdogetparameters #1]->\xprocesscommaitem #1
                                             ,],\@relax@
l.162 	]

Addition of "\def\c!spine{}" makes the error go away.

So definitely something is broken in the latter release for the start- 
macro(s).
Could there be given a quick fix sothat I can avoid reverting back to  
the earlier version or adding changes all ver the place?

Hans van der Meer