XSLT-1.0 can a variable be used to access to other nodes? - variables

Question

With a simple XML like this
<value>
<num>
<accession>111</accession>
<sequence>AAA</sequence>
<score>4000</score>
</num>
</value>
I want to know if it is possible to access to a particular node from a node previously stored in a variable. The XSLT code is very short and explains better what I want to say
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
<xsl:template match="/value/num">
<xsl:variable name="node">
<xsl:copy-of select="current()"/>
</xsl:variable>
<root>
<xsl:copy-of select="$node"/>
</root>
</xsl:template>
</xsl:stylesheet>
So I store the node in the variable "node". Then I can print the contents of the node with $node.
(EDIT) XML output
<root>
<num>
<accession>111</accession>
<sequence>AAA</sequence>
<score>4000</score>
</num>
</root>
What I want to do is to print the contents of a sub-node, like this
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
<xsl:template match="/value/num">
<xsl:variable name="node">
<xsl:copy-of select="current()"/>
</xsl:variable>
<root>
<xsl:copy-of select="$node/accession"/>
</root>
</xsl:template>
</xsl:stylesheet>
But it gives an error (Component returned failure code: 0x80600008 [nsIXSLTProcessor.transformToFragment]) (check here)
(EDIT) The XML that I would want is
<root>
<accession>111</accession>
</root>
NOTE: The question is not how can I get this output. The question is how, using a variable as in the XSLT provided, can I get this output.
(EDIT:SOLVED)
Actually it is possible, but as pointed out in the comments, the value of a variable has to be assigned with the "select" attribute if a node-set is required. So this code was not working since the variable had a tree fragment instead of a node-set stored in it (read more information here)
Thanks!

Answer 1

Try this:
<xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
<xsl:template match="/value">
<root>
<xsl:for-each select="num">
<xsl:variable name="node" select="current()" />
<xsl:copy-of select="$node/accession" />
</xsl:for-each>
</root>
</xsl:template>
</xsl:transform>
Note that I used xsl:transform instead of xsl:stylesheet. Also, consider using version 2.0 instead of 1.0 if you have a compliant processor, it adds a lot of useful features.
I still don't see your need for a variable, though.