Hi Soren and colleagues,
The site bug reporting interface kept trashing my attempt to report this.
 
9.0: XML and XSLT run fine
9.1: same transform on same files generates Saxon 9B -999 error
 
Can I zip up the xslt and just enough of the XML to recreate this for you?  The xml is large.
 
Thanks,
Holly Hendricks
Mass. Historical Society