This problem only affects Java applications using
Saxon to process XPath expressions directly, without
an XSLT stylesheet.
A NullPointerException occurs if you try to evaluate a
Union expression (e.g. a|b) from a Java application
using a Context object that does not refer to any
Controller. In fact the problem is more general than
this: a Controller is needed for two classes of
(a) those that use XSLT-specific functions (such as
key() or format-number()
(b) those that require sorting of nodes, potentially
from multiple documents, into document order.
Expressions in the first group should fail cleanly if
called in a free-standing environment without a
stylesheet. Expressions in the second group should
work, but at present they work only if the documents
concerned are present in a document pool owned by a
Present in 6.5, 7.0, and all earlier releases.
Reported by Yves Bekkers [email@example.com]