Two of these can permanently drop the UID to 1000. The other two however results in a state where a previous privileged state can be restored. Can you spot which ones are right and which ones not? And most importantly: why?

$< = 1000;
$> = 1000;

$> = 1000;
$< = 1000;

$< = $> = 1000

$> = $< = 1000