Difference in template rule processing XSLT 1.0 vs 2.0 - xslt-2.0

Question

Answering another XSLT question on this site, I stumbled on a difference between XSLT 1.0 and 2.0 that I don't understand. Who can explain what is happening here, and how the difference may be resolved?
Note: I am using XML Spy version 2011 sp1 (x64).
My input XML is
<?xml version="1.0" encoding="UTF-8"?>
<root>
<Manager grade="10" id="26">
<Employee id="1" grade="9"/>
<Employee id="2" grade="8"/>
</Manager>
<Manager grade="10" id="27">
<Employee id="3" grade="9"/>
<Employee id="4" grade="8"/>
<Employee id="5" grade="4"/>
</Manager>
<Manager grade="7" id="28">
<Employee id="6" grade="8"/>
<Employee id="7" grade="7"/>
<Employee id="8" grade="6"/>
<Employee id="9" grade="9"/>
</Manager>
<Manager grade="9" id="29">
<Employee id="10" grade="9"/>
<Employee id="11" grade="8"/>
<Employee id="12" grade="7"/>
</Manager>
</root>
I wish to select the set of Employees that have a grade larger than or equal to the managers grade. For this I wrote the following 1.0 transformation:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="/">
<root>
<xsl:apply-templates select="root/Manager"/>
</root>
</xsl:template>
<xsl:template match="Manager">
<mgr>
<managerId><xsl:value-of select="#id"/></managerId>
<managerGrade><xsl:value-of select="#grade"/></managerGrade>
<empsSelection>
<xsl:copy-of select="Employee[#grade >= ../#grade]"/>
</empsSelection>
</mgr>
</xsl:template>
</xsl:stylesheet>
The output is the expected
<?xml version="1.0" encoding="UTF-8"?>
<root>
<mgr>
<managerId>26</managerId>
<managerGrade>10</managerGrade>
<empsSelection/>
</mgr>
<mgr>
<managerId>27</managerId>
<managerGrade>10</managerGrade>
<empsSelection/>
</mgr>
<mgr>
<managerId>28</managerId>
<managerGrade>7</managerGrade>
<empsSelection>
<Employee id="6" grade="8"/>
<Employee id="7" grade="7"/>
<Employee id="9" grade="9"/>
</empsSelection>
</mgr>
<mgr>
<managerId>29</managerId>
<managerGrade>9</managerGrade>
<empsSelection>
<Employee id="10" grade="9"/>
</empsSelection>
</mgr>
</root>
But when I change the XSLT version to 2.0 (take above stylesheet and change stylesheet/#version to 2.0), I get the below different and unexpected result:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<mgr>
<managerId>26</managerId>
<managerGrade>10</managerGrade>
<empsSelection>
<Employee id="1" grade="9"/>
<Employee id="2" grade="8"/>
</empsSelection>
</mgr>
<mgr>
<managerId>27</managerId>
<managerGrade>10</managerGrade>
<empsSelection>
<Employee id="3" grade="9"/>
<Employee id="4" grade="8"/>
<Employee id="5" grade="4"/>
</empsSelection>
</mgr>
<mgr>
<managerId>28</managerId>
<managerGrade>7</managerGrade>
<empsSelection>
<Employee id="6" grade="8"/>
<Employee id="7" grade="7"/>
<Employee id="9" grade="9"/>
</empsSelection>
</mgr>
<mgr>
<managerId>29</managerId>
<managerGrade>9</managerGrade>
<empsSelection>
<Employee id="10" grade="9"/>
</empsSelection>
</mgr>
</root>
Why is this and how should the stylesheet be changed in order to get the correct result in both XSLT 1.0 and 2.0 version?

Answer 1

I think with XSLT 2.0 you by default get comparison as strings while with XSLT 1.0 the comparison operator converts any operands to numbers first which are then compared so with XSLT 2.0 you need
<xsl:template match="Manager">
<mgr>
<managerId><xsl:value-of select="#id"/></managerId>
<managerGrade><xsl:value-of select="#grade"/></managerGrade>
<empsSelection>
<xsl:copy-of select="Employee[number(#grade) >= number(current()/#grade)]"/>
</empsSelection>
</mgr>
</xsl:template>
to get the result you want. Of course using other number types like xs:integer(#grade) should do as well.