After this thread, I realised I had forgotten a great deal about Kosta (and everything else) so I went back to read 'Kosta 250," the book produced as part of Kosta's 250th anniversary. It seems that there was even greater variation in the signature system than I thought, particularly in the late 50's/60's. For example, they have examples of Ventana with no code and signed Mona Morales, Mona Schildt, and Mona Morales-Schildt. The book lists every master blower and cutter who records say worked at Kosta and yet it doesn't provide a list of the code numbers for the designers.
David