A dataset containing the names of all functions available in Excel. This is
useful for identifying user-defined functions in formulas tokenized by
A character vector of length 600.
Pages 26--27 of Microsoft's document "Excel (.xlsx) extensions to the office openxml spreadsheetml file format p.24" https://docs.microsoft.com/en-us/openspecs/office_standards/ms-xlsx/2c5dee00-eff2-4b22-92b6-0738acd4475e, revision 8.0 2017-06-20.
Note that this includes future function names that are already reserved.