What is this icon on the ad?

[sergiuria]

What is that icon on the red square? It shows at the start of the ad, around the 2 second mark.

I haven't seen mention of it anywhere.

And sorry if this has been discussed, I couldn't find it.

 

[mattpen]

It's the button to turn on slideshow mode when the iPad is locked or in the dock.

 

[sergiuria]

Great. Thanks!