The autographic feature was patented, owned, and offered by Eastman Kodak only. Geaorge Eastman himself purchased the patent from the inventor in 1913 for the princely sum of $300,000 and that was a LOT of money back then. It was then used on the majority of cameras Kodak manufactured from 1914 to around 1931.
There are two important elements to the autographic feature, one on the cameras, and one concerning the film.
Autographic film was no different than any other roll film, but it had an unusual double layer paper backing instead of the conventional single layer. The outer paper backing was actually ever so slightly transluscent so that direct light did indeed penetrate it. The inner paper backing was a carbon impregnated material that was opaque, but would be rendered transluscent wherever a sharp instrument pressed against it and compacted the carbon compound. The film came on a spool like any other standard roll film, was loaded into the camera like normal film, and the outer paper backing had exposure counting numbers on it that could be seen through the little red window on the back of cameras like typical roll film. To make the autographic part of the film "work", you needed the camera to have the other half of the autographic elements...
An autographic camera had a little door on the back, placed just above the top edge of the image area, and a special little metal scribing tool. Whenever the photographer wanted to make a note about a particular picture he was taking, the little door was opened, the scribe was used to write and press the message against the little portion of paper backing exposed in that space, the pressure of the scribe caused the inner carbon layer to compact and become transluscent under the tip of the scribe, and the resultant slight bit of light that passed through the lines of the scribed message left an image on the film. When the film was developed, you would see the scribed message along the uppper margin of the photograph!
The autographic feature was the very first form of data back on a camera!
As films became more sensitive, the process became more difficult to control (sensitive films were more likely to fog from that extra light bouncing around in the camera), and there were other more exciting innovations occuring in the photographic community by the 1930's, so the autographic feature was retired. However, there remain zillions of autographic Kodaks out there from that period, and there can be no greater testament to the idea's success and importance.
(Information via Allexperts, Images via Retronaut)