I understand that it stands for Pyro-Metol-Kodalk. I understand that it supposedly gives most excellent results. What I don't understand is exactly what the process does. <p> From what I've read, it seems to be a develop-bleach-stain development method. Is that correct? Why (for example) would you choose to use this over a standard development method? <p> Furthermore, which chemical does the development, the bleaching, and the staining?