Thanks folks for the answers
1) There is a specific button marked A/C with a blue light above the heater dials and below the radio, to the left of it is the recirculation lever, and to the left of that is the demister button.
2) The demister button has on it a dual outline of the rear window AND the mirrors.
This is the reason for my question - the spec seems to be off
Can post a photo if needed.