1.2 Final, Nightly Builds
According to string() function defintion:
"A node-set is converted to a string by returning the string-value of the node in the node-set that is first in document order. If the node-set is empty, an empty string is returned."
Following XPath calculated incorrectly:
string(/MAIN/B | /MAIN/A)
Expected result: "avalue"
Actual value: "bvalue"
sorting of result nodes is missing from CoreOperationUnion