* result stored in $this->filterMatchType.
*
* @param string $input a filename or string containing the XML element
- * @param callable $filterCallback (optional)
+ * @param callable|null $filterCallback (optional)
* Function to call to do additional custom validity checks from the
* SAX element handler event. This gives you access to the element
* namespace, name, attributes, and text contents.
* Alternative constructor: from filename
*
* @param string $fname the filename of an XML document
- * @param callable $filterCallback (optional)
+ * @param callable|null $filterCallback (optional)
* Function to call to do additional custom validity checks from the
* SAX element handler event. This gives you access to the element
* namespace, name, and attributes, but not to text contents.
* Alternative constructor: from string
*
* @param string $string a string containing an XML element
- * @param callable $filterCallback (optional)
+ * @param callable|null $filterCallback (optional)
* Function to call to do additional custom validity checks from the
* SAX element handler event. This gives you access to the element
* namespace, name, and attributes, but not to text contents.