I am using drupal 7 with the devel module. I want to inspect the page variables so I can understand better about the page construction. After I click on theme info I can click on the page.tpl.php template and see a listing of array 35 elements. But $page['content'] is not there even though at the top of page.tpl.php (the commented section) says it should be available. If I do

<?php
dpm
( get_defined_vars());
?>
I can see $page['content']. I am not understanding what themer info is showing me. Thanks, obviously a noobie.