The "1921" Sydney cars, according to specific items of rolling stock, received the following reclassifications upon receipt of electrical equipment:
Control Motor Cars - CB (first-class); CF (second-class).
Non-control Motor Cars - NB (first-class); NF (second-class).
Control Trailer Cars - DB (first-class); DF (second-class).
Non-control Trailer Cars - TB (first-class); TF (second-class).
These generic codes were also applied to the "Standard" steel cars prior to 1940.