An SLK file is a file saved in the Symbolic Link (SYLK) format created by Microsoft to transfer data between spreadsheet programs and other databases. It contains lines of text delimited by semi-colons that specify the cell row, column, formatting, and content. SLK files are stored in an ANSI text format.

Complex formulas are stored with SYLK (Symbolic Link) codes, such as "E," which denotes an expression within a cell. NOTE: SLK file may also be saved as .SYLK files but they are less common than SLK files.