PHPTemplate and printing out available variables for Drupal

List of available varialbles in Drupal 6, 7: http://api.drupal.org/api/drupal/modules--system--page.tpl.php
http://drupal.org/phptemplate
Excerpt from this link:

Print the variables array

<?php
print '
';
print_r(get_defined_vars());
print '
';

?>

Print the variables array with the HTML markup

<?php
print '
';
print htmlspecialchars(print_r(get_defined_vars(), TRUE), ENT_QUOTES);
print '
';

?>