PDX - Adobe Acrobat Index File is great when it comes to creating documents as well as viewing programs right on your computer. You will need to make sure though that you add this extension if you want to be able to view these files. This file extension will allow all users to search multiple PDF documents. It comes in handy for businesses that use large sets of different PDF documents as well as lawyers. These file can also be made under a few different options that you must follow in Adobe Acrobat. You can add many other files if you already have a PDX index using the very same option that you have been using before. You can gain access to this file extension online. Again, it really only comes in handy if you are using Adobe Acrobat.