I have an Excel spreadsheet that gets up to date values from an external
source using RTD. At the end of the day, I save the sheet. If I open the
sheet and my external source is not available, I have a choice to update, or
not update the sheet. Even if I choose, DO NOT UPDATE, the values go to NA
(because the external data source is not there).

Is there a way to save the values in the sheet so that even though my
external source is not available, I can view the last values that were saved
in the sheet?