Vintage service manuals : colour coding?

I have always wondered why the vintage (1960s and 1970s) service manuals are in different colours. They don’t seem to relate to model type (I.e. Beomasters in blue) so what is the reason?

If anyone knows I would be interested!

Ben

Anyone? Is it just random perhaps?

 

Well, indeed there seemed to be a pattern from the late 60s to the early 80s.

Beomaster and Beocenter green

Beogram blue

Beovision yellow

etc.

but that pattern faded away during the 80s.

 

Martin

Martin I agree the 1970s manuals seem to follow that pattern. This doesn’t seem to follow with SMs from the mid 60s where the colours seem not to follow this pattern. I wondered if they were issued as a set each year to dealers and repair workshops which would explain the colours and the tabs on the right side!

Not important, but just curious!

Ben