STDU Viewer is computer software, a compact viewer for many computer file formats: Portable Document Format, World Wide Fund for Nature, DjVu, comic book archive, FB2, ePUB, XML Paper Specification, Text Compression for Reader, Mobipocket, AZW, multi-page TIFF, text file, PalmDoc, Windows Metafile, Windows Metafile, bitmap, Graphics Interchange Format, JPEG-JPG, Portable Network Graphics, Photoshop Document, PiCture eXchange. Wikipedia