The extension WK3 identifies tables (spreadsheets) of the spreadsheet Lotus 1-2-3 from IBM. The extension was used by version 3 of Lotus 1-2-3.
The file contains data in cells organized in columns and rows. In addition, the files may also contain graphics, formulas, and macros. Unfortunately, these macros may also contain malicious code, which is why it is advisable, especially for files from unknown sources, to subject them to virus scanning before executing the macros.
Originally developed by Lotus Corporation, Lotus 1-2-3 was a popular spreadsheet as part of Lotus SmartSuite in the 1990s. IBM acquired Lotus in 1995. The Lotus SmartSuite is discontinued but is still available.
Some versions of Microsoft Excel support Lotus 1-2-3 files, but from version 2007 onwards. The import of files is subject to restrictions, some properties may be lost.