The not function evaluates a boolean expression and returns the opposite value.
Syntax
not(expression )
Arguments
expression- The expression is evaluated exactly as if it were passed as an argument to the boolean() function.
Returns
True for an expression that evaluates to false; false for an expression that evaluates to true.
Notes
- This function should behave similarly to the boolean() function except that it returns the opposite value.
- You can test if an element doesn't have some attribute.
<xsl:for-each match="//a[not(@name and @name = 'badname')]">
<!-- iterates over any <a> element in the document, that
either has no 'name' attribute at all, or it has one,
but its value is not "badname". -->
</xsl:template>
Defined
Gecko support
Supported.