The File | Open Excel command opens an .XLS, .XLSX, or .XLSM file using Excel. All commands and features of Excel are available in Grapher when using this command. You can easily create graphs from the Excel window using the Graphs tab commands.
An Excel file opened with the File | Open Excel command cannot be saved to the same file name. Excel locks the file so that it can only be saved in the open Excel window using the File | Save As command. This is an Excel limitation. To save the changes, choose the File | Save As command and save the Excel file to a new file name.
Note: With older .XLS files and the 64-bit version of Grapher, the File | Open Excel command will sometimes open the file directly in Excel, not in the Grapher window. This is because Excel is opening the file in a compatibility mode not supported by Excel's automation interface. The file can be opened in Excel and saved to a newer format to be able to edit the file in Grapher.