consider the following code snippet:

<?
function foo() {
  global $bar;

  $bar="hello";
}

foo();
echo $bar;
?>

in PHP 3 calling foo() will create a global variable $bar
if it doesn't exist

in PHP 4 there will be no $bar after calling foo

i think PHP 4 should behave like PHP 3 here not only due
to compatibility reasons but also due to the "least supprise" rule