is a format developed by Sony for its proprietary Sony Reader devices. Files in this format may contain text and images. The format is XML-based.
XLS format is used to refer to the documents of the program Microsoft Excel. This file is a spreadsheet. All document data distributed and stored in the cells. Each cell has a unique address, which is denoted by letters and Arabic numerals. The cell can contain fixed data, and data in the form of formulas, which bind more cells.