If you are looking for a simple file extension for your PMF files, you will be able to take advantage of PMF - ESRI Published Map File. This is a read only type of file. You will also be able to use this type of file with an ArcReader application. You can also use this type of file to draw limits to data views and different types of layouts, printing and much more. You also have the ability to protect all of your files that are saved under this format using a simple password. You can make sure that all of your data is safe and secure. There are also maps that are published that do not contain geographical data. There are different links you will be able to take advantage of though. You will also need to make sure that you have network access in order to use this file. Overall, it is definitely something that is worth using on your computer if you are looking for something a bit different to give you a little bit of assistance.