Couple of us arguing about this and none of us can remember what this is or would be called. Commonly seen on forms where you are moving an option from one box on the left to a box on the right and commonly has buttons in between the two boxes to move a singular option or all options. Crude visual example below (since we can't remember it enough to search for an actual example).
------------ -------------------
| Option 1 | | Selected Option |
| Option 2 | -> | |
| Option 3 | --> | |
| Option 4 | <- | |
| Option 5 | <-- | |
| Option 6 | | |
------------ -------------------
What would this be called?
...and, no, you don't have to tell me how mind-blowingly and award winning my illustration is. I am aware. :)