Corpsmen are marines who were required to provide Emergency First Aid on the battlefield. Due to a lack of medic training, Corpsmen are simply marines who, in addition to having the standard UA GPR-12, use a combat shield for added protection and a nanite injection device that produces effects similar to the medic's heal. Though inexperienced, many Corpsmen later move on to either becoming full fledged medics, or they decide to return to their marine duties. Produced during a time of conflict, the Corpsman is often the first on the scene of injury, and the reason marines survive when the real medics arrive.
A Corpsman is capable of producing a healing beam of nanites, regenerating marine armor at a fairly rapid pace at the expense of energy. Note that the Corpsman is not equipped to deal with any sort of ailment.