  In this paper, we focus on a special class of ideal projectors. With the aid
of algebraic geometry, we prove that for this special class of ideal
projectors, there exist "good" error formulas as defined by C. de Boor.
Furthermore, we completely analyze the properties of the interpolation
conditions matched by this special class of ideal projectors, and show that the
ranges of this special class of ideal projectors are the minimal degree
interpolation spaces with regard to their associated interpolation conditions.
