Moving Parametric Primitive

Moving parametric primitives are a subset of parametric geometry that follows a user-prescribed trajectory through space over time. Parametric moving geometry can be attached to particle and scalar field parents, as well as global variable parent objects. For particle and scalar field parents, these moving bodies can define a moving addition or sink region. For global variables, these objects can model a moving analysis region. This function is discussed on the Parametric Moving Geometry.

(or should we just fold that documentation in the page here?)