RGMc
RGMc refers to a specific classification or designation within a particular system, likely related to engineering, manufacturing, or quality control. The "RG" portion could stand for a company, a department, or a type of component, while "Mc" might indicate a model number, a revision, or a manufacturing batch. Without further context, the exact meaning of RGMc is ambiguous.
It is common for industries to use alphanumeric codes to identify and track products, processes, or materials.