Setting a dirty flag for a file

[Charles Szasz]

I am using Rev. 4.0. How do you set a "dirty flag" for a data file that that has been saved but still open in your app stack?  My app creates a data file that saves the contents of 16 fields. I have code to show an initial save dialog when the user makes changes. I want to use a dirty flag to show another save box only when closing the file if the user makes subsequent changes in the data file.  Otherwise when the user closes the data file without additional change no save dialog will be presented.

Thanks for your time! 

Charles Szasz
cszasz at mac.com