Can we declare global variable and add/Remove/Check value from it? - xslt-1.0

Question

I want to achieve
Declare global variable having no value
<xsl:variable name="IsEqual"/>
Check variable value and change according to condition
<xsl:choose>
**// Checking value equal or not**
<xsl:when test="name=$name">
<xsl:choose>
**//Checking variable value**
<xsl:when test="$IsEqual !='Unequal'">
**//Setting variable value**
<xsl:variable name="IsEqual" Select="Equal"/>
</xsl:when>
</xsl:choose>
</xsl:when>
<xsl:otherwise>
**//Setting variable value**
<xsl:variable name="IsEqual" Select="Unequal"/>
</xsl:otherwise>
</xsl:choose>
<xsl:value-of select="$IsEqual"/>
Expected output value of variable $IsEqual.. IF it is not possible then what is another way to achieve this? What should I use instead of variable?

Answer 1

"It's not a bug, it's a feature": XSLT variables are designed not to be changeable. Actually they could be named constants. Working around that is difficult, it can be done using parameters. In most cases that isn't necessary if you use the XSLT programming attempt, where the programm is driven by the data through templates.
The answer to your question is no.
Copied this (own) text from XML and Variables
#Sam: What do you want to accomplish using a global variable? Where do you want to check for equality? I have no idea what you want to do so I can only give you a general example.
Try this xml file:
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="test.xsl"?>
<root>
<data check="value1">This is data 1</data>
<data check="value2">This is data 2</data>
<data check="value3">This is data 3</data>
</root>
with this xslt file:
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:variable name="v">value2</xsl:variable>
<xsl:template match="/">
<xsl:apply-templates select="root/data[#check = $v]"/>
</xsl:template>
<xsl:template match="data">
<xsl:value-of select="."/>
</xsl:template>
</xsl:stylesheet>
Only the second data element will show up as this one matches the global variable, which stays the same all the time. If you want different values to match with, you can put them into your data file instead using a variable and compare the different elements.
For testing just save the two files (test.xml and test.xsl) into one directory and open test.xml with your browser.
#Sam again: As you insist on changing an xslt variable I have to repeat that this can't be done. Maybe there is a way around using the environment xslt is running in. E.g. PHP, where you can pass functions into the script. I described the technique here: Can PHP communicate with XSLT?
The xslt spec says:
XSLT does not provide an equivalent to the Java assignment operator
x = "value";
because this would make it harder to create an implementation that processes a document other than in a batch-like way, starting at the beginning and continuing through to the end.
(See http://www.w3.org/TR/xslt#variables to prove my answer "no" to your question is correct :-)