Simple retraction of maxillary incisors using maxillary molars as anchorage is an example of:

Dental anchorage in which the manner and application of force tend to displace the anchorage unit bodily in the plane of space in which the force is being applied is termed stationary anchorage. If a tooth can be grasped with an appliance in such a manner that any movement requires the tooth to move without any change in its axial inclination, this resistance is considerably greater than a tipping force. A good example of this type of anchorage is the retraction of maxillary incisors, using the first molars as the anchorage unit.