Whatever happened to Feynman's notation (27.3 of vol 2) for vector differential identities? Ever since I learned his notation of subscripting nabla with the vector field it acts on to treat nabla as a plain vector, I have been using it to derive all vector identities I need. I only need to resort to indices when homework requires it, but otherwise I use it exclusively. I see so little mention of this notation that I get the impression that most people do not find it useful. What is your impression?