/*  pex :: Php Extensible eXplorer
*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*|-|
* File :       WhatIsThis.txt                                                             *|-|
* Description: Mini help page for "data" folder.                                          *|-|
*                                                                                         *|-|
* To Do :      Create a real manual                                                       *|-|
*                                                                                         *|-|
*                                                                                         *|-|
*                                                                                         *|-|
*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*¨*|-|
*/

Now... what is the data folder?

It is the default data folder (Wow, now that's complicated). By default, in the "/index.php" file, there's the line:
	  $GLOBALS['start']="data";

It just means that pex will take the folder data as the root folder. If you open the page index.php, it'll show what's in "data" first.
Still, you can change the value of $GLOBALS['start'] for ".":
	  $GLOBALS['start']=".";

Instead of looking for the data folder, it will look in the folder where pex was installed.