There was a universal function bar for the 15's. But, there was very little application for it. The Auto CR/LF mods used that function bar to trip them off (solenoids, etc.). Those mods were non-Teletype Corp. inventions. All TTY Corp. machines had some sort of "universal function bar", from the Model 14's through the 37's. Even the 28 reperf has a code-able function bar! JAck WA2HWJ