Allyn,
I think it is a matter of word usage, but fat is usually considered raw. Beef fat is often called tallow when raw, or rendered, pork fat is called lard when rendered, beef fat becomes tallow when rendered; but I reserve the right to mix up my terms. There was quite a thread on the topic about a year ago, including cooking and purifying methods. I believe JW said you can get a very white tallow by boiling it in water, but start heating them at the same time! I would suggest doing it outdoors!
Hawkdancer