The file index.php ia very simple one, it has the task to load on the main PHPNuke page the module that was chosen as the default one to appear in the main page of our site.
Here in detail what happens when it the page index.php gets loaded:
the mainfile.php is included,
a database query is made in order to see which module was set up as the default one,
the origin of the visitor is checked (if he comes from a site that links us, this fact will be inserted in a table of the database).
Moreover various checks are made and error messages are defined for the case that the connection to the database fails. This avoids (in part) that error messages of the PHP preprocessor itself appear in the output. Even if problems come up, the page will be presented in a standard design and the error message will be definable from the inside.
