fn:zero-or-one

Tests whether a given sequence contains zero or one items; fails if it contains multiple items.

zero-or-one($arg as item()*) ➔ item()?

Arguments

 

$arg

item()*

The input sequence to be tested

Result

item()?

Namespace

http://www.w3.org/2005/xpath-functions

Links to W3C specifications

XPath 3.1 Functions and Operators