Required 

m: 

If your application contains collections that follow the range selection model, BAdjust is supported and behaves just like Shift+BSelect, when the BTransfer button is currently configured to behave as BAdjust. 

Required 

n: 

Reselect

The extended range is determined by the anchor and the current pointer position, in exactly the same manner as when the selection was initially made. 

Enlarge Only

The selection can only be enlarged. The extended range is determined by the anchor and the current pointer position, but then is enlarged to include the current selection. 

Balance Beam

A balance point is defined at the midpoint of the current selection. When the user presses Shift+BSelect or BAdjust on the opposite side of the balance point from the anchor, this model works exactly like the reselect model. When the user presses Shift+BSelect, BAdjust, or starts a navigation action modified by Shift on the same side of the balance point as the anchor, this model moves the anchor to the opposite end of the selection and then works exactly like the reselect model. 

When the user releases BSelect or BAdjust, the anchor does not move, all the elements within the extended range are selected, and all the elements outside of it are deselected.