In article , Alan Browne
wrote:

Fullframe still means 35mm film sized frames.

If so, what is the "frame" in a digital camera? It certainly is not an
ASP-C sensor.

Full frame is 36x24mm. FF digital sensors are typically within less
than a mm of that size. The Sony a7 III for example is 35.6 x 23.8mm.

film is slightly less than 36x24mm due to slide mounts and negative
carriers.

being within a fraction of a millimeter is insignificant.