note 15286 added to language.operators.comparison

here is a valid example of how parens affect use of the ternary operator in a chain. With parens the first true value is returned, otherwise the LAST true value is returned. $a = 5.5; <? $b = ($a < 0 ? '0' : ($a < 1 ? '1' : ($a < 2 ? '2' : ($a < 3 ? '3' : ($a < 4 ? '4' : ($a < 5 ? '5' : ($a < 6 ? '6' : ($a < 7 ? '7' : ($a < 8 ? '8' : 'foo' ))))))))); ?> ($b == '6') without parens: <? $b = $a < 0 ? '0' : $a < 1 ? '1' : $a < 2 ? '2' : $a < 3 ? '3' : $a < 4 ? '4' : $a < 5 ? '5' : $a < 6 ? '6' : $a < 7 ? '7' : $a < 8 ? '8' : $a == 'cheesemonkey' ? 'eek' : $a < 10 ? '10' : 'foo' ; ?> ($b == 10) http://www.php.net/manual/en/language.operators.comparison.php