Hi, it is correct this is not possible. Although please leave the issue open as a feature request.

It's very easy to implement for XSLX since they are stored as plain text in the XML. But XLS'es save formulas in a bytecode which needs to be "decompiled". Additionally the XLS formula bytecodes are variable length, which means we have to implement everything at once. The first step to implement XLS formulas would be to create some test data, i.e we need a spreadsheet containing every possible Excel formula.

Hi thanks, I thought that the binary might be causing the problem :-/

here is your first step: https://github.com/spreadsheetlab/XLParser/blob/master/src/XLParser.Tests/data/enron/formulas.txt