This is where the file type that you want to add or delete goes. A file type is a unique signature which consists of 4 characters. It is used to identify the function of a file.
Click on this button if you want to delete this file type from the list you are editing. The file type is deleted only if it is found in the list.
Click on this button if you want to keep this file type in the list or add this file type to the list you are editing.