where is the source code for "Powered by Drupal" Someone told me the footer text "Powered by Drupal" in Drupal7 is provided by theme_system_powered_by(), which is turned into a block by system_block_info() and system_block_view(). I wonder in what file(s) these functions can be found. Thanks a million.
Here's the API documentation for all your needs:


theme_system_powered_by()
system_block_info()
system_block_view()


Also, please note that modifying the output of theme_system_powered_by() should be done using a theme hook from your theme code. If you wonder how to achieve this, this might be a relevant article for you.