Middleswarth

http://drupal.org/node/171224

highlights

regions[left] = Left sidebar
regions[right] = Right sidebar
regions[content] = Content
regions[header] = Header
regions[footer] = Footer

A few notes:

* There are template (.tpl.php) files available for rendering individual blocks.
* Adding a custom region prevents the defaults from being used. If you want to keep the defaults in addition to custom regions, manually add in the defaults.
* The order in which the regions are defined will be reflected in the block configuration table. Garland for example uses the default regions. Notice the order of the regions listed in the image.
* The contents of the .info file is cached in the database so altering it will not be noticed by Drupal. (Do not confuse this with the theme registry.) To clear it, do one of the following:
1. Clear button located at "Administer > Site configuration > Performance".
2. With devel block enabled (comes with devel module), click the "Empty cache" link.
3. Simply visit the theme select page at "Administer > Site building > Themes".

Upgrade notes:

* In Drupal 5 and below, regions were declared with ThemeName_regions() or EngineName_regions(). It has been deprecated in Drupal 6.
* If you are upgrading your theme from versions before Drupal 6 and the region variables of $sidebar_left and $sidebar_right were used, rename them to $left and $right.
* The $footer_message region variable in versions before 6 mixed the footer region with the footer message (set from "Administer > Site configuration > Site information"). Make sure a separate $footer variable is created if your theme uses it since Drupal 6 and above no longer combines the two elements.