The read-only sheet property of the ProcessingInstruction interface contains the stylesheet associated to the ProcessingInstruction.
The xml-stylesheet processing instruction is used to associate a stylesheet in an XML file.
The associated Stylesheet object, or null if there are none.
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/css" href="rule.css"?>
…The sheet property of the processing instruction will return the StyleSheet object describing rule.css.