Before Model 5 ist Model...6? – Progress (Janalif) typewriter

According to research by Alex Sandler the Soviet Progress 5 typewriter was not introduced in 1940 but in 1942. The previous model he guessed could have been Model 4. Now I have found this photography from Межреспубликанский журнал No. 26 from 1940: The banner is saying: The first experimental model of the typewriter Progress M-6. The machine itself looks like a Janalif Model B (1932–40): The typewriter on the right is a Janalif Model A produced 1929–32: What is strange is the name M-6. Somebody knows more? –– It reminds of Indian Godrej where the first model was M-9 and its successor M-8. Click here for Godrej .