The format of linkable, relocatable, and absolute object modules is specified. MUFOM, the Microprocessor Universal Format for Object Modules, is designed to apply to a variety of target machines. It permits the linking and relocating functions to be isolated from the specification of target architecture, so that a user may employ a single program for these functions across all CPUs. It applies to binary computers of arbitrary word size and architecture. Two levels of compliance are specified, minimum and full. The minimum compliance level affords sufficient flexibility to link separately compiled modules, to relocate addresses in simple ways, and to load the resulting absolute object modules with a minimal loader. The full compliance level affords all of the functionality of the minimum level and adds to it arbitrary address-expression handling, type checking capability, librarian control commands, and other useful functions for full generality.