In the actual template, it is clearly documented that the
(nearly corresponding) IPP attribute is called 
'generated-natural-language-configured'.  At several IPP WG
telecons, we have had concensus (I think) that it is
unreasonable for a (potentially non-IPP printer) to 
have 'printer-location', etc, supported configured
in a different language than 'natural-language-configured'
(both SLP and IPP attribute).  Therefore, the template
presumes that 'natural-language-supported' gives a good
set of values to choose a 'natural-language-configured'
value from.
Hope that helped.  PLEASE read the following message closely
(referring to the latest text of the SLPv2 'printer:' template
as well) and send comments.
Cheers,
- Ira McDonald
  High North Inc
  716-461-5667 (w/ voice mail)