PHP: array('function' => 'theme_select_as_checkboxes')

Seems like declaring an associative array. With sucha an array, you can retrieve the content of the array this way :

$myArray = array('function' => 'theme_select_as_checkboxes');
echo $myArray['function']; // Prints 'theme_select_as_checkboxes

No magic in here ! ;)

its just an associative array and unless some context is given, doesnt mean anything special!

Appears to be a function/method name that can be called at a later time. Other than the data, it looks to be just a standard array.

You may be interested in this question as well: How to call PHP function from string stored in a Variable.

this is not a special structure. http://en.wikipedia.org/wiki/Associative_array http://www.bellaonline.com/articles/art31316.asp