> + and - seems used for input numeric mesures

I don't think that + is, but - definitely is. This is so if for example you're drawing a line, you can type "-5,2" to place a point at that coordinate directly.

When you type that coordinate value, your keystrokes will show up in the coordinate value entry area in the bottom toolbar, just to the right of the Split/3D/Top/Front/Right view controls.

- Michael