When Hospital Corpsmen are assigned to Marine units, they are typically referred to as "Corpsmen" or "Doc." This term is commonly used by Marines to address their assigned Navy Hospital Corpsman, regardless of their rank.
For example, if a Hospital Corpsman is an E-4, which is equivalent to a Marine Corporal, they would still be addressed as "Corpsman" or "Doc" by the Marines they are serving with, rather than using their specific rank (e.g., Petty Officer Third Class) when addressing them informally.
Using "Corpsman" or "Doc" to address the Hospital Corpsman emphasizes their primary role as medical personnel and fosters a strong sense of camaraderie and mutual respect within the unit. It also reflects the close relationship between Marines and their Corpsmen, as the Corpsmen are responsible for providing medical care and support to the Marines they serve alongside in often challenging and dangerous situations.