Impotant for Drupal 7 Theming

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General Utility Variables
$base_path    The base URL path of the Drupal installation.
$directory      The directory the template is located
$is_front          TRUE if the current page is the front page.
$logged_in      TRUE if the user is registered and signed in.
$is_admin        TRUE if the user has permission to access administration pages.
Site Identity
$front_page  The URL of the front page.
$logo              The path to the logo image
$site_name  The name of the site
$site_slogan  The slogan of the site
$highlight     Replace of a $mission
$title_pre!x    An array containing additional output populated by modules
$title                The page title
$title_su”x      An array containing additional output populated by modules
$messages       HTML for status and error messages
$tabs          Tabs linking to any sub-pages beneath the current page
$action_links      Actions local to the page
$feed_icons        A string of all feed icons for the current page.
$node             The node object

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