XLS file format
XLS – is a spreadsheet created by a popular Microsoft Excel application. It includes document data that is located in cells that have a specific address. They can contain formulas, mathematical equations associated with the information in other cells, and fixed information. It is often used for the development of graphs and charts. The format allows us to store and edit a broad range of parameters - images, tables, macros, types, diagrams. It has been widely used until the appearance of the 2007 version of Excel, and then it was replaced with the XMLSS extension. The information inside the XLS document is contained in a series of static-size streams. Their location is described using several segment distribution tables. It differs in backward compatibility and supports various file formats created for DOS. It is often used by web browsers to exclude the use of binary formats. The utility is included in the Microsoft Office suite and, in addition to Excel, can be opened by various applications like Apache Open Office, Libre Office, adapted to Mac OS, Windows, or Linux.
The format's relevance is explained by its simplicity, although it does not support separate functions, for example, storing VBA macros. Until XMLSS appeared, the Excel application used the Biff extension when formatting, created based on the IFF container format. Due to this, changes to the book templates and their contents were available. After introducing the new format in 2007, the program has not lost the backward compatible properties, which guarantees the wide distribution of XLS in the future. Subsequently, the XLS extension was replaced by the XLSM, XLSB, and XLSX formats.