File | Export as tab delimited text file
This allows you to create a text file from a Markbook90 grid which can then be loaded directly into a spreadsheet such as Microsoft Excel (R).
Choose Tab delimited text file as the file type, and type in an appropriate filename and location. Save the file.
The saved file should then be openable in Excel, for instance. Using File | Open in Excel, and selecting this file, will lead to several windows appearing asking you to confirm the structure of the file. You should be able to click on Next at each stage, Finish at the last stage, to open the file. The screenshots below show the required responses, if your machine is not set up to default correctly.