 Thus, the image of formula_309, denoted by formula_334, forms a space of distributions when it is endowed with the strong dual topology of formula_335 (transferred to it via the transpose map formula_336, so formula_337's topology is finer than the subspace topology that this set inherits from formula_46).The elements of formula_334 are the distributions of order ≤ "k".Note that the distributions of order ≤ 0, which are also called distributions of order 0, are exactly the distributions that are Radon measures (described above).