After entering data in a RealData product under Excel 2007, when you try to save your work, you may see this message:
This document is both encrypted and password protected. The Office Open XML Formats available in the 2007 release provide stronger encryption. Do you want to increase the security of this document by converting to an Office Open XML Format?
The safest thing to do is click “No”. This will cause the file to be saved as an Excel 97-2003 Workbook (*.xls), which is quite reliable. If you click “Yes”, the file will be converted to an Excel Macro-Enabled Workbook (*.xlsm), which has some benefits, but runs the risk of having macros disabled.
The issue of stronger encryption is probably not relevant for you as a user, anyway. The encryption protects the VBA project (our software code), not your data which remains visible when someone opens the file.
It’s true that an Excel Macro-Enabled Workbook (*.xlsm) tends to be much smaller than the corresponding Excel 97-2003 Workbook (*.xls). However, you may find that you cannot enable macros in a file saved in this format if you have Excel 2007 and not updated your install of Excel to the latest release.