Circle with a capital T in it

In the Scrivener app for iPad there is a Circle with a capital T in it at the left hand top of the screen. Select it and it turns dark.
What does this do? So far I haven’t been able to detect it doing anything nor have I found an explanation for the function.
Of course, I’m searching for “Circle with a capital T in it”, which is probably the whole problem.
What is this and what does it do?

It turns on Typewriter Mode.

Great - thanks!

Does anybody know if a keyboard shortcut exists to switch the Typewriter mode on/off ?

None visible in the list of shortcuts. BTW, if you hold down the CMD key on your keyboard a second or two, you get a context-sensitive list of keyboard shortcuts.

I am not around an iPad at the moment to double check, but try Ctrl-Cmd-T, that would be the most likely candidate as that is the shortcut on macOS.

I’m used to the CMD key to show up keyboard shortcuts but I didn’t find the one I’m looking for. I’m not sure but I think I red in another post that some shortcut were not documented. I also remember someone talking about the Typewriter shortcut, but can’t get my hands on it…

Unfortunately, this is not the good shortcut. I have tried all combinations involving the T letter with no luck.