The tooltip should prefer appearing after the wrapper or anchor point on this axis, unless it doesn't fit.
The tooltip should decide whether to place before or after the wrapper on this axis depending on context, with no bias. For example, this could be decided from the anchor position of a tooltip container.
The tooltip should prefer appearing before the wrapper or anchor point on this axis, unless it doesn't fit.
The tooltip should prefer appearing centred around the anchor point on this axis if possible.
The bias to apply to a tooltip's positioning for a specific axis.
For example, the vertical bias helps the tooltip decide whether it should prefer appearing above or below the tooltip wrapper. The horizontal bias helps the tooltip decide whether it should prefer appearing to the left or to the right of the tooltip wrapper.
Depending on the implementation, the tooltip container has no obligation to take these biases into account, however, the default TooltipContainer implementation does. Note also that these definitions are purposefuly vague, and how these are used is left to the implementation. For example, it doesn't make sense to have a centre-biased vertical axis in the default tooltip container implementation, but it does make sense to have a centre-biased horizontal axis.