998 - Special Assignment  

An enlisted Marine regularly performing duties of a highly specialized nature that are not covered by one of the military specialties described in this manual.

870 - CHEMICAL WARFARE SPECIALIST
[CW SPL]

Trains others in defense against gas attack by familiarizing men with methods of detecting and identifying gases, with use and care of gas masks and protective clothing, with decontamination techniques, and with first aid treatment to gas casualties.

837 - COMBAT CONDITIONER  
[CBT CONDITIONER]

Instructs troops in one or more of the following combat techniques:

695 - ORDERLY

Attends and accompanies a commanding or an executive officer and performs such routine duties as delivering and receiving messages, announcing visitors, and running errands.