An AI Anchor is a point or collection of points which can be used by AI to perform a specific action or event, such as an animation or behavior.
Certain smart objects can have special geometry assigned to them, to assist with object placement.
A smart object
A smart object with an additional placement guide
Other AI Smart Object Parameters
Click here for the Miscellaneous Parameters reference guide, here for the Miscellaneous Entity Parameters guide, here for the Entity Links guide and here for the Entity Events guide.