What is the "mode" slider when copying in edit mode for?

when in edit mode, using shit+d to duplicate verts, there is an option that is called “mode”:

Whats it for? Im using Blender 2.91.

Thanks for help!

Don’t worry about it, it’s some internal state passed along to the subsequent transform operator. I’m not entirely sure why it’s even needed, or why it’s exposed like that.

ok, thanks for that information.