.WK1

Introduction

WK1 is the worksheet format of Lotus 1-2-3 Release 2, the spreadsheet that dominated MS-DOS business computing in the 1980s. Release 1A used the earlier .wks, and later releases moved to .wk3 and .wk4, which hold several sheets. IBM, which bought Lotus in 1995, ended the product in 2013. WK1 files still turn up in old archives, and other spreadsheets can import them.

Structure

A WK1 file is a sequence of records, each a 2-byte opcode, a 2-byte length and the data, little-endian. The first record is BOF (opcode 0x0000) holding the file version, 0x0406 for WK1 (.wks files have 0x0404), and the last is EOF (opcode 0x0001). In between come records for the sheet’s range, column widths and settings, then one record per cell: integers, floating-point numbers, labels and formulas, each with a format byte, the column and row, and the value. Formulas are stored compiled, in reverse Polish order.

Links