does anyone know of a way to determine the type of file without using the file extension? i know there must be a way because this one particular application call ApplicationXtender does this with files. it changes a files extension to a .bin for displaying the image or document, it also changes the name of the file to an id that it stores in the database. if you know which file the id belongs to you can change the file extension to lets say .tif, .pdf, or even .doc and it will work. so i'm assuming that this application is looking at the binary data that's in the file or using some kind of mime functionality to determine the file type.