You know them best as the G staff or the S staff, such as the G1 or the S3. G staff (General Staff at the division level or higher) or the S staff (Special Staff at the brigade or battalion level): G Staff/S Staff. G1/S1: Personnel and Administration; G2/S2: Intelligence and Security; G3/S3: Operations and Training; G4/S4: Logistics and Supply More @Wikipedia
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