Gnumeric talking to Excel.

[Wayne Ward <infotechsys pivot net>]

Hello,
I tried to find a group for Gnumeric questions, but atlas I couldn't.
I hope you folks don't mine me asking this Q. here.
I have a friend who is sending me an Excel sheet which I make some
changes on and sent it back to him. When he trys to show it in Excel
he gets garbage, with a message saying that Excel doesn't understand
the format. Can Gnumeric be used in this way? If so what do I have
to do to make it work?
TIA.
Wayne