Thanks for the response. But, I gotta apologize... Reading over my original question, I realize that it was awfully obtuse and confusing. The 'nohlsearch' line is the one that is already in my .vimrc and works. I yanked/put it to the next line down to use it as a template, modifing it to:
map <F3> :set nobackup <return> that's the one that doesn't work (the <return> part-obviously-works with my original line). I did notice that the highlighting recognized the word 'set' as a command, but did not recognize 'nobackup', which remained white (black?). Thus, I tried: map <F3> ":set nobackup" <return> with no better luck. Sorry for creating the confusion.