$a = false; $b = false; $c = true;
$z = $a || $b || $c; // get true
$a = false; $b = false; $c = true;
$z = $a or $b or $c; // get false
$a = false; $b = false; $c = true;
$z = ($a or $b or $c); // get true
$a = false; $b = false; $c = true;
$z = $a || $b || $c; // get true
$a = false; $b = false; $c = true;
$z = $a or $b or $c; // get false
$a = false; $b = false; $c = true;
$z = ($a or $b or $c); // get true