Correct me if I'm wrong, but this doesn't looks like an documentation issue. Its probably your error reporting thats set to E_ALL, and not E_ALL & ~E_NOTICE so notices will be generated.

You can set the optional second parameter on set_error_handler to ignore notices, eg.:
set_error_reporting('ErrorHandler', E_ALL & ~E_NOTICE);

The issue is that, according to the documentation, the value of the first parameter ($iErr) in my example "will be 0 if the statement that caused the error was prepended by the @ error-control operator."

The undefined index error was pre-pended by the @ error-control operator.  I understand that this will still call my error handler callback, but it should have set the value of $iErr to 0.

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

Says the documentation:
"error_reporting() settings will have no effect and your error handler will be called regardless - however you are still able to read the current value of error_reporting and act appropriately. Of particular note is that this value will be 0 if the statement that caused the error was prepended by the @ error-control operator."

I.e.

<?php

function ErrorHandler() {
	var_dump(error_reporting()); // 0
}

set_error_handler('ErrorHandler');
echo @$a[1];