I have a complete number 4 and there are instructions. Here is what it says about the blades and their use. There are three blades and they are shown and numbered.
"Use coarse knife for cutting fruits, meats and vegetables for stews, soups, goulash, meat pies, etc. Also chicken, veal, etc., for salads and making head cheese."
"Use medium knife for cutting cooked foods, chicken, veal, etc, for croquettes; potatoes and meat for hash, if like fairly coarse; oysters for poultry stuffing, clams, meat loaf and sausage. Also for chopping peppers, raisins, and things of that sort."
"Use fine knife for cutting raw meat for hamburgers, etc. Do not use fine knife for vegetables or juicy fruits."