Symbolic Link (SYLK) is a Microsoft file format typically used to exchange data between applications, specifically spreadsheets. SYLK files conventionally have a .slk suffix. Composed of only displayable ANSI characters, it can be easily created and processed by other applications, such as databases. Microsoft does not publish a SYLK specification. Variants of the format are supported by Multiplan, Microsoft Excel, Microsoft Works, OpenOffice.org, LibreOffice and Gnumeric. The format was introduced in the 1980s and has not evolved since 1986. A commonly encountered (and spurious) 'occurrence' of the SYLK file happens when a comma-separated value (CSV) format is saved with an unquoted first field name of 'ID', that is the first two characters match the first two characters of the SYLK file format. Microsoft Excel (at least to Office 2016) will then emit misleading error messages relating to the format of the file, such as "The file you are trying to open, 'x.csv', is in a different format than specified by the file extension...". SYLK is known to cause security issues, as it allows an attacker to run arbitrary code, offers the opportunity to disguise the attack vector under the benign-looking appearance of a CSV file, and is still enabled by default on recent (2016) versions of Microsoft Excel. Limitations SYLK does not have support for Unicode. Even if a SYLK file is created by an application that supports Unicode (for example Microsoft Excel), the SYLK file will be encoded in the current system's ANSI code page, not in Unicode. If the application contained characters that were displayable in Unicode but have no code point in the current system's code page, they will be converted to question marks ('?') in the SYLK file. The semicolon is treated as a field separator in SYLK, so cannot be used unescaped in data values. If a character string in the SYLK file is to contain a semicolon (;) then it should be prefixed with another semicolon so the string would appear as e.g., "WIDGET;;AXC1254". MS Excel will strip the first semicolon on import and the data element will appear as "WIDGET;AXC1254". Each line of a SYLK input file must be no longer than 260 characters. Otherwise, Microsoft Excel will issue an error message and skip loading the overlong line. Sample SYLK code As an example, the following SYLK code in a text file with the .slk extension: ID;P C;Y1;X1;K"Row 1" C;Y2;X1;K"Row 2" C;Y3;X1;K"Total" C;Y1;X2;K11