Photofact Set Legend (so far)
     
AA   Audio Amplifiers & Associated Equipment
AR   Auto Radio Series
CB   Citizen's Band Radio Series
CM   Automatic Record Changer Series
CP    
CR   Communications Receiver Manual
HF   Hi-Fi & Audio Equipment
HTP   Home Tape Player Series
MHF   Modular Hi-Fi Components
RC   Automatic Record Changers
SD   Scanner-Monitor Servicing Data
TR   Tape Recorder Series
TSM   Transistor Radio Series
TVCR    
VCR