Would PL_YES (!!1) and PL_NO (!!0) be similarly globaller-than-global globals? If so, how would one go about overriding them? Or, are we overriding the undef() function when we do the above-mentioned trick? If so, why aren't we using CORE::undef() instead of the internals trick?
Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.