@Dr-Sassi Hi Dr. Sassi!
Interesting response. On further investigation, I noticed in the Picture Viewer in the 'File' pull-down the 'Save as' options gives one the choice of a 'Type' of which 'Still Image' is one and when it is selected the filename template stuff is greyed out. So, it's just something RS didn't include in it's render settings.
And, Yes, I could just manually save the file but I do depend on auto-saving when the render is complete because I'm not always around when it finishes.
I will make a suggestion as you said.
Cheers,
Greg