The tag can be controlled by Fields. To do so, enable the Use Fields option in the Basic Properties menu.
The Fields list can contain various position-dependent Fields. Imagine, for example, a Spherical Field that has a specific position. If the object to which the tag is assigned is deformed by a deformer/effector, for example, the position of the object points/clones, etc. will change. If the Spherical Field should affect the deformed or non-deformed element state, this is the option that should be used.
This option must be enabled if, for example, a character animated with joints (or elements of a matrix controlled by an effector) should move through the Spherical Field and the Spherical Field should take effect when the character passes through.
See for example Field.