Recollections of BBC engineering from 1922 to 1997
The British Broadcasting Corporation
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Coded Equipment



Designs Department Manufacturing Information (DDMI) was produced for every item of equipment that was designed in the Department. This enabled Equipment Department or external companies to make quantities of the item. Prior to about 1970 these documents were called Specifications.

A typical DDMI contained a description, test procedure, parts list, circuit diagram and assembly drawings (including printed circuit board, metalwork etc.).  All of the papers were contained in an A4 cardboard folder that was typically 1.5 cm thick.  The paper sizes ranged from A4 to A1.  They were numbered in the form 8.202(65) meaning, in this example, that it was designed by Section 8 in 1965 and the document has the serial number 202.