boolean

The boolean() function calculates the effective boolean value of the supplied argument. Every XPath value, of any data type, has an effective boolean value that is either true or false . The rules for calculating the effective boolean value are given in the entry for <xsl:if> in Chapter 5.

Argument	Data Type	Meaning
value	item()*	The value whose effective boolean value is required
Result	xs:boolean	The effective boolean value of the argument. This is false if the supplied value is an empty sequence or if it is a sequence consisting of a single value that is the boolean false , a number equal to zero, NaN , or a zero-length string; in all other cases, the result is true