STDU Viewer is described by its author as
View all most popular documents formats by one program.
STDU Viewer supports many text based formats and can present them in an unobtrusive and somewhat attractive interface. It tries to centralize the task that may require several programs. For example notepad to open *.txt files and a PDF viewer to open *.pdf files. To that end STDU Viewer supports TXT, TIFF, PDF, DjVu, CBR, CBZ and XPS file formats. The program has some interesting and useful features that perhaps make it more useful for some. Using the View menu it is possible