DOCBOOK-APPS: Total number of pages in dsssl ?

I'd like to get a page numbering like "page 1 of 10", and can't find a
documented way of getting the number of pages in an element.  I found
`total-node-page-numbers' mentionned in the DSSSL standard (section
12.5.1.2. Layout Numbering), but
(total-node-page-numbers (sgml-root-element)) makes jade unhappy (E:
reference to undefined variable "total-node-page-numbers")

Regards,
-- 
Yann Dirson <>                 http://www.alcove.com/
Free-Software Engineer				      Ing幯ieur Logiciel Libre
Free-Software time Coordinator	       Responsable du temps Informatique Libre