Tip about register globals set to "on"

I did some coding on a site where register_globals is set to on. The
problem I encountered was that the session variable changed without my
changing it explicitly. I knew that in register globals being on, that
all the variables were global variables. What I didn't realize was that
it set up an equivalence such that the variable is an alias for the
session variable with the key name of that variable. That is,
$_SESSION['key'] is the same as $key.

I got around the problem by changing the key of the the session variable
to something unique.

Here is a little test script:
<?php
session_start();
$_SESSION['company'] = 'This';
print '1: ' . $_SESSION['company'] . '<br>';
$company = 0;
print '2: ' . $_SESSION['company'] . '<br>';
$_SESSION['company'] = 'This';
print '3: ' . $_SESSION['company'] . '<br>';
$company = 'That';
print '4: ' . $_SESSION['company'];
$foo = 'Foo';
print '5: ' . $_SESSION['foo'] . '<br>';
?>

Here is the output:
1: This
2: 0
3: This
4: That
5: Foo