A40 - pre-flash/ AF assist beam?

[airliner]

I have a question on the operation of flash. I am reading the English version of manual. On page 54, (Using the flash > Notes section) it is mentioned that 'The flash fires twice. A preparatory pre-flash is followed by the main flash. The exposure readings obtained from the subject with the pre-flash are used to set the optimal flash intensity for the main flash, which is used to shoot the image.'

Is this referring to the AF assist beam (orange color illuminator)? Or is this a white flash of the same character as the main flash (but fires before the main flash when the shutter button is pressed half way)? I do not find any particular flash mode that illustrate a pre-flash other than the orange color AF assist beam. Any input from the expert here would be appreciated.

airliner

[Conk]

Simple. Set your camera on auto and make sure it is set to flash. Push the button down half way. There should be no flash yet. Now push the button the rest of the way. There are 2 flashes in very quick sequence. It is so fast that you may not be aware of it.
This is not related to the AF assist beam that is referred to on page 39.