Is based on the XML format. Its main tasks are: precise display on a variety of devices, full preservation of document structure, ability to be transformed into other formats. Unlike other popular e-book formats, fb2 does not specify the appearance options for different devices’ displays. The format employs tools to indicate the different parts of the book – verses, epigraphs, quotations.

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.