2534 Calc602 Spreadsheet file 1.00 Text (Structured) Files generated by Calc602, a spreadsheet programme made by Software602 which was released in 1988 by Czechoslovakian company 602 Svazarm (since the 1990s known as IT company Software602). Tc6 is the native file format for Calc602.The bak file backs up content, and has exactly the same internal signature as the tc6 file. 242 The National Archives of the Czech Republic / The National Archives of the Czech Republic 13 Jun 2022 28 Oct 2022 fmt/1698 PUID bak File extension tc6 File extension 2031 Calc602 Spreadsheet file v.1.00 Absolute from beginning of file, magic bytes: Software602 Calc602 v.1.00 Tabulka 1 Absolute from BOF 0 0 536F6674776172653630320D0A43616C6336303220762E312E303020546162756C6B61 Has priority over 2623 Calc602 Spreadsheet File