What is a "Remaining" Context?

I’ve been an OF user for quite a while, and I am revisiting some of my custom perspectives (using OF2). One of the contexts I use a lot I call “T|T|F” (or Today|Tomorrow|Flagged), which is what most people use as a “Today” perspective—it shows all tasks that are due today, due tomorrow, or flagged.

In the Perspectives window, Filtering section, I’m having trouble understanding why there is an option to filter by “Remaining” Contexts. Actions can be “Remaining”, but Contexts can only be Active, On Hold, or Dropped.
Can anyone help me understand why “Remaining” is an option for filtering Contexts, and what happens when this option is selected?

TIA!

In my view, the remaining should be treated as activate + on hold