Dave Nichols discovered cake, a predecessor of GNU make, and taught our laboratory how to use it. Jon Claerbout conceived the idea of reproducible research documents. He and Martin Karrenbach wrote cake rules for the four basic commands burn, build, view, and clean. Joel Schroeder and I redesigned the system from scratch and implemented in GNU make, a standard UNIX tool. We appreciate Richard Stallman's advice and his implementation of the special built-in target .SECONDARY. Bill Symes reviewed the ReDoc rules carefully. I thank him for his good-humor and suggestions.