📄`.`❓

#file extension #dot extension #filename extension #file type identifier #unknown file type #file association

📄`.

#file extension #file type #document format #filename suffix #dot extension

📄`.`🔤

#file extension #file type #document format #suffix #dot extension #file naming

📄.`???

#file extension #dot extension #file format specifier #file name extension #file kind #unknown file type