This might sometimes be useful, if for example you are only interested in (1) if (2) is true. That is,

unparsed-entity-uri(ancestor::ipb/figure/subfig/graphic[@boardno=$sht_num]/@boardno)

will return a URI if (and only if) $sht_num appears as a @boardno on an ancestor::ipb/figure/subfig/graphic, and is also declared as an unparsed entity (with a URI not ''); otherwise it will be ''.

So why did my when clause testing against the '' (empty string) not fire? That was my first impulse.

Cheers,
Wendell

======================================================================
Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.                http://www.mulberrytech.com
17 West Jefferson Street                    Direct Phone: 301/315-9635
Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
----------------------------------------------------------------------
  Mulberry Technologies: A Consultancy Specializing in SGML and XML
======================================================================