| check_plain | drupal/includes/bootstrap.inc | Encode special characters in a plain-text string for display as HTML. |
| check_url | drupal/includes/common.inc | Prepare a URL for use in an HTML attribute. Strips harmful protocols. |
| l | drupal/includes/common.inc | Format an internal Drupal link. |
| module_exists | drupal/includes/module.inc | Determine whether a given module exists. |
| t | drupal/includes/common.inc | Translate strings to the page language or a given language. |
| theme | drupal/includes/theme.inc | Generate the themed output. |
| user_access | drupal/modules/user/user.module | Determine whether the user has a given privilege. |