This series consists of correspondence files that contain information regarding suspect activities of certain people or organisations. The contents include passport applications; investigations; notices of departures and arrivals of peoples with suspected enemy sympathies in Australia and overseas allied countries; security irregularities; secrecy of information derived from censorship; release of internees; nominal register; indexes and photographs of party members of Fascist organisations in Australia; Japanese business interests; return of secret treated mail. Most correspondence is between the Commonwealth Investigation Branch Canberra and Department of Defence.

The records are arranged by a single number in groups with each group being indenified by the alphabetical prefix. The prefixes are as follows:
C    - Chinese
CIB  - Commonwealth Investigation Branch
F    - French
I    - Internees
IC   - Indo-Chinese
J    - Japanese
MISC - Miscellaneous
P    - Policy
S    - Security
SAB  - Sabotage
SFA  - [Secret Fascist Associations?]