[Audacity-quality] Left pointing grey arrow in the Timeline

[Steve t. F. <ste...@gm...>]

While working on the Timeline icons, I noticed this and it struck me
as odd - what does this symbol actually mean?

When there is no selection, there is a grey icon in the Timeline in
the shape of a vertical line with a left pointing arrow pointing at it
"|<"

What is the significance of that icon?

It clearly does not mean "go left from here", though that could be an
interpretation.

Is it perhaps intended to be the start arrow of a play region?
That seems more reasonable, but if so, why a different (larger) icon
rather than reusing the start arrow of the play region?

The symbol also looks similar to the "Rewind" button icon "|<<" but
that is obviously not it either. So I'm left wondering, what does this
icon actually mean?

Considering that there is already a thin black vertical line
indicating the cursor position, does this icon communicate any
additional information to the user? If so, what?

Steve